Man United hero Roy Keane reveals why Arsenal will always struggle in Europe

The Gunners lost their opening Group A tie with Dinamo Zagreb last night and had Olivier Giroud sent off.

Arsene Wenger's side went down 2-1 at the Stadion Maksimir after an own goal from Alex Oxlade-Chamberlain, Junior Fernandes' second half header and Theo Walcott's late effort.

And former Manchester United midfielder Keane believes Arsenal's weaknesses were exposed by the Croatian side - and will be again and again.

"It's what I expect from Arsenal, they are short," Keane said on ITV.

"Looking at the spine of the team, the players in the middle of the park.

"They were up against it down to 10 men but roll up your sleeves and get the job done. You feel Arsenal have a weakness through them. 

"I still expect them to get out the group, obviously in second. Further in the competition they do come up short though."

Wenger made six changes last night, including swapping David Ospina for Petr Cech, but insisted the Gunners would bounce to qualify for the knockout rounds.

They face Olympiakos at the end of the month before the double header against Bayern Munich

"Mathematically we can qualify without any problem if we can produce our performances that we want at home," Wenger said.

"We have had problems starting in every competition this season.

"We were slow starting the Premier League and now the Champions League. 

"I’m confident that we can put that right in the next five games."