Arsenal were devoid of their characteristic free-flowing football and attacking adventure, but they got the job done against Olympiacos to post a second successive win in the Champions League.
Gervinho and Lukas Podolski were the goalscorers as Arsenal came from behind to win in Montpellier two weeks ago, and the same players netted once again at the Emirates Stadium, with a goal from Kostas Mitroglou sandwiched between, and a late strike from Aaron Ramsey.
Arsene Wenger, in the stands again to serve his UEFA suspension, was able to field vice-captain Mikel Arteta from the start after he passed a fitness test, while Alex Oxlade-Chamberlain was preferred to Ramsey.
Abou Diaby's injury against Chelsea resulted in a forced change in midfield - with Francis Coquelin deputising - while Gervinho and Podolski were once again selected ahead of Olivier Giroud.
The Gunners hardly deserved their lead when it came courtesy of Gervinho in the 42nd minute, after the Ivorian had turned on the edge of the box and fired neatly past Balazs Megyeri from 18-yards.
It was Gervinho's fifth goal of the season, and reinforced his place above Walcott in Wenger's centre-forward pecking order.
Olympiacos were level just three minutes later - on the balance deservedly so - as Mitroglou rose above the Arsenal defence and headed past Vito Mannone on the stroke of half-time.
Santi Cazorla - less influential than previous games - had the opportunity to reclaim the lead shortly after the break, but could only shoot wide after Gervinho had huffed and puffed down the right.
It was Gervinho, in a similar position, who laid on the winner for Podolski shortly before the hour, with the German latching onto a drag back from six yards out.
Arsenal looked the most dangerous for the remainder of the encounter, but still lacked the courage and skill usually seen from Wenger's side, but Ramsey's fresh legs ensured they netted another before the close.
Picking up the loose ball, the second-half sub strode past the tiring Olympiacos players and lifted the ball over an advancing Megyeri. It was a far from vintage performance, but it was a decent job done in the end.