Arsenal 3-1 Cologne, Europa League RESULT: Night of fan trouble at the Emirates sees Alexis Sanchez, Sead Kolasinac and Hector Bellerin turn it around after invasion of thousands of visiting supporters delayed kick-off

Thanks for following our live coverage this evening. Here's how Arsenal's group looks at this early stage... a welcome sight for Gunners tonight ahead of their trip to Chelsea on Sunday:

90+2 mins: That's it, the referee blows up and a night of drama on and off the pitch ends with a home win for Arsenal.

They took their time to get there - an hour pre-match delay and a Jhon Cordoba wondergoal holding them back - but they eventually triumph with goals from Sead Kolasinac, Alexis Sanchez and Hector Bellerin.

Three points give them an ideal start to their Europa League campaign on a less-than ideal evening otherwise courtesy of a quality second half.

89 mins: They're 3-1 down, but all you can hear is Cologne fans at The Emirates now.

But it's Arsenal playing all the football. Their latest move sees backheels from Wilshere and Olivier Giroud eventually end up with Sanchez chip just about missing the target in a real show of the Gunners' footballing ability.

83 mins: Another sub for Arsenal. 17-year-old Reiss Nelson gets his chance, coming on for Walcott.

82 mins: That will settle it. Hector Bellerin - game over.

Sanchez again leads the charge, bringing the ball down the left flank but squaring it across the edge of the area this time into the path of Wilshere who unselfishly dummies to set up Walcott.

He wastes the opportunity, shooting straight at the keeper but the power is too much and Bellerin slides in the rebound.

78 mins: Another chance for Sanchez as he races through, put through by Jack Wilshere, but his shot is a little wild from a less than ideal angle and the chance is gone.

75 mins: Sanchez has a chance at a second here with a free-kick, albeit from very long range... it's a dipper but well-saved by Horn and he holds to avert any danger from the men rushing in.

68 mins: Amid all that madness, Jack Wilshere is back on a football pitch for Arsenal to huge cheers from the home crowd.

He replaces Alex Iwobi.

67 mins: Fantastic goal from Alexis Sanchez - Arsenal are ahead!

The Chilean forward looks every bit worth the £60million Manchester City wanted to pay for him on deadline day as he creates and scores this goal all on his own.

Sanchez was alone, dashing down the left touchline after Alex Iwobi's ball went too wide. From there, he drifted in, away from a defender, away from another - nothing on... so he opened up his body and dinked a super finish in from just outside the area.

Excellent, excellent goal. 2-1.

64 mins: Excellent run by Ainsley Maitland-Niles but he really must score there.

The 20-year-old from Ilford jinks his way past a challenge and all of a sudden he's in on goal, faced one-on-one with keeper Timo Horn.

It looks a little like he couldn't make up his mind, though, and when he perhaps should have dinked it over the keeper Horn is quickly out to sweep away. Big chance.

Meanwhile, Cologne withdraw Simon Zoller for Marcel Risse.

61 mins: A quick reminder that Cologne aren't out of this... Hector Bellerin loses the ball in his own half and suddenly it opens up a little bit for Leonardo Bittencourt.

The former Hannover man unleashes a shot at goal from range and although it looked a bit tasty it's straight at David Ospina, who saves with ease.

57 mins: Arsenal have been far better in this second half and they look well on the front foot after Kolasinac's equaliser.

The Cologne fans have quietened down too, a little - although they're now serenading the Arsenal supporters with a chorus of 'You only sing when you're winning'.

49 mins: Arsenal are level, and it's the substitute Sead Kolasinac.

It all starts as Elneny advances through midfield and chips a ball through to Theo Walcott that the Englishman has to take wide.

He tries to cross into the box but it's nodded out - only as far as Kolasinac who powers home a left-foot volley across the goalkeeper and in with a well-controlled strike from the angle.

All of a sudden you can hear the Arsenal fans again. They're back in this.

Official attendance at The Emirates tonight is: 59,359. We'll leave it up to you to guess how many of those are away fans...

46 mins: We're off again and there's a substitution for Arsenal - Rob Holding is off for Sead Kolasinac.

Looks like a change in system from Arsene Wenger.

Results from tonight's other 8.05pm Europa League kick-offs...

All images from Sportsmail's GRAHAM CHADWICK:

45 mins: Ainsley Maitland-Niles is shepherded out of play and Arsenal go in at half-time a goal down on a night that their stadium and their hopes of winning this game have been fiercely attacked by the visitors.

The thousands of Cologne fans around The Emirates will be delighted with how things are going after Jhon Cordoba's 10th-minute wondergoal following David Ospina's error.

Sportsmail's Adam Crafton reports:

The Met police confirmed to Sportsmail that four people have been arrested as part of the policing operation surrounding the match.

39 mins: Great run by Alex Iwobi to get Cologne thinking and he opens up space to spread the ball wide to Alexis Sanchez on the right.

Sanchez jinks away from his marker and dinks a perfect cross in to Olivier Giroud, who looks set to score but he sends it wide. He perhaps should have netted the equaliser, there.

35 mins: Jonas Hector looks like he was hurt in that collision with Ospina - perhaps his ankle has been twisted by the way the Arsenal goalkeeper went through him.

He's back up on his feet but coming off injured. Replaced by Milos Jojic.

30 mins: That was another big moment in this game. Fantastic curling ball around the back of the defence from Konstantin Rausc almost reaches Simon Zoller but Ospina, who has looked shaky all night, tips the ball away from him.

Jonas Hector tries to follow up but he's felled by Ospina. Fortunately for Arsenal the whistle had already gone for offside on the initial chance.

23 mins: Ooh, that's the best chance of the game so far for Arsenal and Theo Walcott snatches at it.

Alex Iwobi plays a ball over the top and the England forward is onside but he scuffs his shot under pressure and it goes wide. Promising signs for the hosts, though.

20 mins: More good movement from Arsenal.

They go wide down the right this time with a galloping Hector Bellerin overlapping and his cross is well-directed to Olivier Giroud but the Frenchman can't get enough power on the header and it's easily saved.

Here's the goal that gave Cologne their shock lead:

15 mins: Arsenal have responded well since that Cologne goal, which has sparked flares going off and loud chanting all around the ground.

The Gunners are working their way forward a lot better now and they win a corner, taken by Alexis Sanchez and headed by Nacho Monreal - but straight at the goalkeeper.

10 mins: It is the goal UEFA, the Metropolitan Police and Arsenal all feared - Cologne lead at The Emirates.

This game has been meandering along and then all of a sudden a moment of wonder from Jhon Cordoba sees the home and away ends erupt together.

A hit-and-hope ball over the top looked to be posing little danger until David Ospina intervened - the goalkeeper rushing out to clear it, terribly.

Cologne scrambled possession to the feet of Cordoba and from fully 40 yards he turns and shoots over the goalkeeper's head and into the back of the net. A brilliant goal.

4 mins: Two flares in the away end. Four minutes in - quickly extinguished.

3 mins: Chants of 'Arsenal, Arsenal' ring up from the stands at The Emirates, but they are being regularly drowned out by the constant whistles from the thousands of Cologne fans whenever the Gunners have the ball.

On the pitch, the opening few minutes have been fairly uneventful. Theo Walcott has just been knocked off the ball after a strong Arsenal passing move went awry.

1 min: We're underway at The Emirates.

Here's the scores from the other games... It's half-time everywhere else:

FCSB 2-0 Plzen

Red Star Belgrade 0-0 BATE

Zorya Luhansk 0-0 Ostersunds

Guimaraes 1-1 Salzburg

Hapoel Beer Sheva 1-0 Lugano

Hertha Berlin 0-0 Athletic Bilbao

Marseille 0-0 Konyaspor

Real Sociedad 3-0 Rosenborg

Vardar 0-3 Zenit St Petersburg

Vitesse 1-0 Lazio

Waregem 0-3 Nice

Kick-off, at last, is just minutes away. Red-hot atmosphere at The Emirates... and it's not particularly pro-the home side.

ARSENAL (3-4-2-1): Ospina; Holding, Mertesacker, Monreal; Bellerin, Iwobi, Elneny, Maitland-Niles; Walcott, Sanchez; Giroud.

COLOGNE (4-1-4-1): Cordoba; Bittencourt, Hector, Hoger, Zoller; Lehmann; Rausch, Heintz, Mere, Klunter; Horn.

Further reports of seriously bad behaviour among a selection of Cologne fans in the streets of London as the north part of the city still feels the fall-out from this game...

A home game for Arsenal tonight? Perhaps not judging by this footage from inside the home concourse.

We're also hearing talk of more Cologne fans buying Arsenal shirts to try to work their way into the home end. Bizarre.

Games of football are taking place at grounds other than The Emirates. Here's how the other 8.05pm Europa League games look at around the half-hour mark:

FCSB 1-0 Plzen

Red Star Belgrade 0-0 BATE

Zorya Luhansk 0-0 Ostersunds

Guimaraes 1-0 Salzburg

Hapoel Beer Sheva 1-0 Lugano

Hertha Berlin 0-0 Athletic Bilbao

Marseille 0-0 Konyaspor

Real Sociedad 2-0 Rosenborg

Vardar 0-2 Zenit St Petersburg

Vitesse 1-0 Lazio

Waregem 0-3 Nice

Sportsmail's Matt Barlow at The Emirates:

Cologne fans singing loudly and bouncing. But fans are bouncing in all parts of the ground. They’re in the top tier of the Clock End and parts of the ground which really should be Arsenal only.

Here's some video footage from the ground, showing a widespread Poznan being conducted across the home and away ends.

This game is going ahead, with Arsenal briefing that the situation is 'under control' and that playing will be the 'safest option'. Kick-off is in half an hour at 9.05pm.

Cologne players out. Huge roar. The away end is packed. The rest of the ground is, well, like it usually is 40 minutes before kick off at the Emirates.

Good prospects for this game going ahead on the pitch, at least: The Cologne goalkeepers are out to warm up.

An update from Sportsmail's MATT BARLOW at the Emirates Stadium:

Fans are coming in. Several Cologne fans are already filing into the Arsenal seats with scarves and shirts on and then trying to get into the away end with a few skirmishes.

There is a ring of riot cops around the away seats now.

Still no final decision on whether it goes ahead. But one will be made soon. If it can't go ahead at 9.05pm, the match may be called off.

There are now police dog units inside The Emirates working in a bid to prevent those Cologne fans who are in the home end from charging their way into their away section.

The game was due to kick-off right about now but Arsenal vs Cologne has been delayed by an hour until 9.05pm BST due to fears over crowd safety.

Police dogs are now inside the Emirates in an effort to keep order, and police have been sent to the flashpoint area down in the away end.

It appears as though Cologne fans who have made it into the home section at the Emirates are making their way to the away end, hurdling the barrier and joining the travelling supporters.

Stewards aren't stopping them at the moment.

Sportsmail reporter Jono Spencer is in among the fans tonight and he says: 'Well Cologne fans got in the home end without any trouble. Sitting right next to some...'

There has been some trouble in the away end inside the Emirates, with minor scuffles between Arsenal and Cologne fans.

It was quickly diffused by the stewards.

There are still very few supporters in the stadium.

More fan footage, this time from inside the Emirates...

Turnstiles are now open.

Scenes from outside the Emirates. 

- Arsenal face Cologne in the Europa League at the Emirates Stadium tonight

- Cologne fans flooded through London during Thursday afternoon, marching up Oxford Street and into the roads of Islington

- The fans have been largely good-natured

- Around 20,000 are believed to have travelled despite the club only being handed an allocation of 2,900

- The gates at the Emirates were not opened to fans until 55 minutes before kick-off

- The bridge to the stadium had to be cordoned off by police, penning fans in away from the ground

- Kick-off has been delayed by one hour, to 9.05pm BST, due to fears over crowd safety

- There have been reports of some Cologne fans storming a gate, which are unconfirmed

- Arsenal supporters report being unable to make their way around the outside perimeter of the stadium to get to their seats

No suggestion of any violence among the Cologne fans but the time it is taking to clear the number of ticketless supporters has caused the delay.

Most of the problems appear to be on the bridge across to the Emirates and outside gate K.

Another view of the outside of the Emirates shows just how big the police presence is.

Blues and twos going off outside the ground as police and stewards try to bring calm to the area...

Problems here. Turnstiles not open yet. Fans told there will be a 60-min delay. Lots of Cologne fans camped outside locked gates at the home end. Fears clearly that they have acquired tickets in the home end.

Arsenal say the sheer volume of Cologne fans outside the ground are preventing Gunners supporters from getting into the stadium.

There are also fears that visiting fans have gained tickets in the home end, while there are reports elsewhere of Cologne supporters 'storming the gates'.

An announcement has just gone out over the tannor at the Emirates: 'The match has been delayed by 60 minutes'.

No reason behind it just yet.

As shown in the picture below, the police cordons around the Emirates have had to hold strong this evening under the weight of thousands of travelling supporters.

Police have been holding fans outside the Emirates Stadium for a long time, and have only just started allowing a trickle of supporters into the ground.

Remember, there are an expected 20,000 Cologne supporters in London today and plenty of security issues for the authorities to consider as a result.

Cologne supporters have reportedly stormed the barriers at the Emirates ahead of their side's Europa League match against Arsenal.

Reports over an hour before the game suggested that German fans were held back outside the stadium before they broke past police lines and headed for the turnstiles.

It is believed that at least one Cologne was left with a bleeding head.

READ THE FULL STORY HERE

Cologne XI: Horn, Klunter, Mere, Heintz, Rausch, Lehmann, Zoller, Hoger, Hector, Bittencourt, Cordoba.

Subs: Kessler, Sorensen, Risse, Jojic, Osako, Guirassy, Horn 

Jack Wilshere only makes the bench for Arsenal.

Arsenal XI: Ospina, Mertesacker, Holding, Monreal, Bellerin, Elneny, Maitland-Niles, Iwobi, Walcott, Sanchez, Giroud.

Subs: Macey, Wilshere, Mustafi, Reine-Adelaide, Kolasinac, Akpom, Nelson

And welcome along to Sportsmail's coverage of Arsenal's return to the Europa League.

Cologne are the visitors to the Emirates tonight and, if you live anywhere near Islington, you'll know that all too well.

The Germans have been in tremendous voice on the streets of London today and they're likely to make an almighty racket inside the stadium.

It should be an occasion to savour, and you're in the right place to follow all the action.