Arsene Wenger's side improve in the second half, after an even opening period, to stutter their second consecutive Champions League victory so far this term
Lukas Podolski and substitute Aaron Ramsey struck in the second-half to brighten up a largely uninspiring display from Arsene Wenger’s side after they struggled to break down their well organised opponents for much of the evening.
Not that the Frenchman will care after a result that leaves Arsenal with six points from their opening two Group B fixtures and on course for another comfortable qualification for the second round of Europe’s elite competition.
The hosts controlled possession but lacked attacking thrust for much of the game, taking the lead against the run of play through Gervinho in the 42nd minute before Konstantinos Mitroglou deservedly levelled for Olympiakos on the stroke of half-time.
Podolski eased nerved in the Emirates Stadium after firing home in the 56th minute and Ramsey sealed the three points with an impudent finish with the last kick of the game.
While Arsenal displayed their usual domination of possession in the early exchanges, their central defensive pairing of Thomas Vermaelen and Laurent Koscielny were so casual, they were virtually horizontal.
Mitroglou served a warning as his snapshot from the edge of the penalty area was saved by Vito Mannone before Paulo Machado missed a gift-wrapped chance, mishitting from inside the six-yard box after evading Arsenal defenders to meet Ioannis Maniatis’ cross.
Arsenal took a lead they barely deserved three minutes before the break through Gervinho. After excellent work from Santi Cazorla on the left, the ball broke for the Ivorian to shift into space and strike low into the corner from 20 yards for his fifth goal of the season.
The strike was met with relief all round from the home crowd but Olympiakos deservedly levelled on the stroke of half-time. Leandro Greco whipped in a wonderful cross from the left and Mitroglou was on hand to glance the ball into the far corner.
Arsene Wenger may not have been allowed in the dressing room at half-time due to a touchline ban but his anger with his side’s lack of attacking thrust would have been relayed to his players.
They responded after the break, especially through the twinkling toes of Cazorla and Gervinho as the latter began to torment the Olympiakos back four with his movement and trickery.
Cazorla wastefully shot wide from 12 yards before Podolski doubled the Gunners’ lead in the 56th minute, the German taking advantage of Olympiakos’ uncertain defending to swivel in the box and shoot low and hard through goalkeeper Balazs Megyeri’s legs.
Arsenal went hunting for a third. Koscielny headed over unmarked before substitutes Theo Walcott and Olivier Giroud combined for the Frenchmen to volley straight at Megyeri.
In the dying seconds, substitute Ramsey raced on to Giroud's flick-on and scooped a delightful finish over the goalkeeper and into the back of the net.
Olympiakos still showed enough to prove they will no whipping boys and Arsenal face a difficult return fixture, but they cruised home in the closing stages to complete the victory.