Two-goal Alexis Sanchez shot Arsenal to within a point of the top four.
The Chilean superstar smashed two goals - his seventh and eighth in the Premier League this season - in four second half minutes to see off Crystal Palace.
The victory ended a nightmare run of just two wins away from home in the League so far this season for Arsene Wenger's side.
It also saw the Frenchman equal Sir Alex Ferguson’s record 810 Premier League games in style.
Defender Shkodran Mustafi had put Arsenal ahead with a close range finish on 25 minutes. But Andros Townsend hit a scintillating equaliser on the run four minutes after the break.
James Tomkins sparked an anxious climax for the Gunners when he headed home with a minute remaining but Arsenal held on for a vital victory.
They now travel to West Brom on Sunday while Palace boss Roy Hodgson must prepare his players to host Manchester City on the same day.
1. Landmark night for Wenger
hat a way to celebrate reaching the magic number. Wenger matches Sir Alex Ferguson’s 810 Premier League games in charge with this contest.
Fergie may have lifted five titles since Wenger’s last but you have to salute Wenger’s refusal to give in to the critics who believe he should join his former adversary in cracking open the pipe and slippers.
Here Wenger showed you actually can teach an old dog new tricks, bouncing back from last year’s shock defeat here to confound the statisticians. Arsenal had managed to win just two (two!) away league games this season before this.
It was a victory that was needed. We know they won’t win the Premier League but they are hanging in there for a top-four place.
2. Hodgson gives Palace hope
Don’t write Palace off based on this result. In fact more power to his elbow for the way in which he inspired his players to force their way back into it after the break.
Credit to Hodgson too for sticking it to the critics who believed that at 70 - two years older than Wenger - he was too old for a Premier League return.
What short-sighted nonsense to write off a man who had saved West Brom and Fulham from the drop and had worked with some of the most celebrated footballers in the world before some of his current charges were born.
Bear in mind that when Hodgson succeeded 47-year-old Frank de Boer, Palace were bottom of the league with zero confidence and zero points - five points from safety.
Inspired by Hodgson, they went into this game on an eight-match unbeaten run, their longest in the top flight since a 12-match sequence 27 years ago. That run might now be over but Palace are far from finished.
3. Sanchez leaves souvenirs for Gunners
There must be so many mixed feelings at Arsenal over this performance from the Chilean superstar. For the past month he has been way below his best. Here he decided to turn up and he was simply unplayable.
Yes, he will have left Arsenal fans drooling but they will also be fuming that Sanchez is basically marking time before he walks out of the front door - for free - to whatever Premier League club he chooses next summer (*cough* Manchester City).
It has been fascinating to watch Arsene Wenger suggesting, on a week to week basis, that he or Arsenal have any kind of control of the situation.
Performances like tonight are simply souvenirs for the Gunners boss and the club to hold on to when Sanchez is wearing light blue next season.
4. Zaha shines once again
How they laughed when the Crystal Palace chairman Steve Parish rejected Tottenham’s interest, insisting his prize asset was worth £40million. Now the north Londoners - and even the biggest clubs in the country - would probably need to stick another £20million on top.
Yes they lost and yes they are still bang in trouble. But Zaha was yet again outstanding and remains crucial to the Palace revival. He is now the player that Manchester United thought they’d signed when they landed him four years ago. He is now the player that would add that x-factor to the Tottenham three behind Harry Kane.
He has become that player, however, because of the faith and confidence that Palace have placed in him. Because of the regular game time he has had to blossom and grow. Now he is determined to pay that love back by leading Palace to safety and helping the club to grow.
5. Wilshere getting better and better
By midway through the second half the travelling Arsenal fans were singing his name. He’d already been trending on Twitter for some time before that.
Jack Wilshere does indeed appear to be back. From the outset the England midfielder, fighting for a new club contract as well as a place in Three Lions’ World Cup squad, looked to have the appetite for the fight.
The statement he was trying to make was obvious as he threw himself into challenges and showed an impressive stomach for the fight. His ball over the top for Sanchez’s second was classic Wilshere. The new and improved version might just be in line for a boarding pass to Russia.