Arsenal legend angered by their last night perfomance

Arsenal's Pierre-Emerick Aubameyang is consoled by Dani Ceballos after the match [David Klein, Reuters]

Former Arsenal defender Martin Keown has criticised the team for their "unprofessional" performance in Thursday's Europa League defeat by Olympiakos Piraeus, which knocked them out of the competition.

Olympiakos forward Youssef El Arabi scored in extra time and sealed a 2-1 win in the round of 32 second-leg clash in London, as the Greek side progressed on away goals after the tie ended 2-2 on aggregate.

Arsenal striker Pierre-Emerick Aubameyang, who scored in the 113th minute to cancel out Pape Cisse's 53rd-minute goal, wasted a late chance that could have sent the hosts through.

"There were so many disappointments in that performance. There were so many unprofessional performances from players. Such a poor game for Arsenal," Keown told BT Sport.

"It was the first time I felt that the players were not responding to the manager and the manager didn't know what changes to make.

"If you break down the performance you could have looked at every player and say they could have all done more. Nicolas Pepe is going to have to improve. Gabriel Martinelli should have come on a lot earlier. Granit Xhaka was taking the easy way out."

Arsenal manager Mikel Arteta said he was pained by the result but refused to blame his players.

"It hurts a lot. It's cruel. It's a massive disappointment but at the same time I'm proud of the players," Arteta said.

"It would have been an incredible lift if we had managed to go through the tie. The players have my backing for the way they played but it's painful."