Champions League: Olympiakos beats Arsenal 2-1

The London side took the lead against the flow of play in the 38th minute with Tomas Rosicky, set up by Gervinho, who switched to the right, outran two defenders and skillfully swung the ball back.

Olympiakos dropped back despite having the early initiative, helped by Algerian duo Djamel Abdoun and Rafik Djebbour, who missed some early chances.

Arsenal captain Thomas Vermaelen stopped successive attacks in central defense before the visitors were eventually overrun at Piraeus' Karaiskaki Stadium near Athens.

But Yiannis Maniatis leveled in the 64th, pouncing on a defensive error when Aaron Ramsey foolishly chested the ball down.

Mitroglou scored the winner in the 73rd, powering the ball past Arsenal goalkeeper Wojciech Szczesny from outside the area, just a minute after coming on.

"We had a good first half, but I believe we dropped physically in the second half because many of the players didn't have the match experience at that level," Arsenal manager Arsene Wenger said.

His whose team had already qualified from Group B, while Wenger marked his 150th Champions League match.

He traveled to Greece without several key players, including Theo Walcott and Lukas Podolski, before the match against West Bromwich Albion in the Premier League on Saturday.