Arsenal were made to work hard for their second Group B win of the Champions League as second-half goals from Lukas Podolski and Aaron Ramsey helped earn them a 3-1 success against Olympiakos at the Emirates Stadium.
Gervinho handed the home side the lead despite an unconvincing team performance when he turned to thump a low shot into the net from 25 yards out on 42 minutes only for a battling visiting team to draw level a minute into added time in the first half when Kostas Mitroglou rose to glance home Leandro Greco's header.
It was certainly a deserved equaliser for Olympiakos, who have now lost all 11 matches to English sides away from home in Europe in as many trips to England.
Arsenal - with manager Arsene Wenger forced to watch from the stands in the second match of his three-match suspension - were an improved lot in the second period.
They moved 2-1 clear when Podolski turned home Gervinho's cutback on 56 minutes with visiting goalkeeper Balazs Megyeri somehow seeing the ball slip through his legs.
Aaron Ramsey completed the scoring to hand the Premier League side a scoreline that probably flattered them when he dashed onto fellow substitute Olivier Giroud's cushioned header to lift the ball over the exposed Megyeri with seconds remaining.
Arsenal move top of Group B on six points with Schalke and Montepellier drawing 2-2 in the night's other match in the section. It is a result that does not harm Arsenal as they try to ease their way into the last 16 of the tournament with games to spare.
A home win over Schalke in a fortnight's time will all but secure Arsenal a place in the knock-out phase.
The one downside of the night was the empty spaces that could be found pockets of the ground for such a fixture in Europe's premier club competition.
The first period saw Arsenal binge on possession with Olympiakos looking livelier in the final third. Santi Cazorla forced Megyeri to tip over a free-kick on 11 minutes, but the visitors blew a golden chance to find the opening goal when Paulo Machado somehow lifted the ball over from Giannis Maniatis's cross 10 minutes before half-time.
With the scoreline level at 1-1, Arsenal appeared more lively after half-time with Cazorla swiping a shot wide from Gervinho's pass before Podolski struck.
Arsenal continued on the offensive as Olivier Giroud and Ramsay replaced Podolski and Gervinho with 10 minutes left. It was Ramsey who had the final word on a soaking evening.
MAN OF THE MATCH
Gervinho - A tough first season for the forward, but is finally beginning to settle. Fine first goal and played provider for Podolski to restore the home side's lead. A valuable contribution on a tough old night for Arsenal.
Arsenal: Mannone 7; Jenkinson 6, Koscielny 5, Vermaelen 6, Gibbs 7; Coquelin 6, Arteta 6; Oxlade-Chamberlain 6, Cazorla 7, Podolski 7; Gervinho 8..subs: Walcott 6, Ramsey 7, Giroud 7,
Olympiakos: Megyeri 5; Diakite 6, Manolas 6 Contreras 6, Holebas 6; Siovas 5, Maniatis 6; Greco 5, David Fuster 6, Machado 5; Mitroglou 6..subs: Carroll, Ibagaza 5, Abdoun 6, Pantelic 5