Substitute Aaron Ramsey scored in stoppage time to hand Arsenal a victory which moved them to the top of Champions League Group F at the expense of opponents Marseille.
The Wales star fired in from just inside the area after Johan Djourou's cross fell into his path.
Robin van Persie had a header cleared off the line before both he and Theo Walcott had low shots saved.
Marseille's Loic Remy went close when his effort was deflected wide.
The win moves the Gunners to seven points, one ahead of the French side and four ahead of third place Olympiakos.
Arsenal manager Arsene Wenger will be delighted with the result although the match itself was poor on quality.
Possession was more or less evenly shared, but both sides frustrated by giving the ball away cheaply.
There were very few clear-cut chances in the match, although Arsenal created the lion's share.
Van Persie went close when his looping header was cleared off the line by Souleymane Diawara from Mikel Arteta's corner.
What referee Damir Skomina and his assistants did not notice was that Marseille's hero of the moment had initially handled when the corner was delivered.
The Arsenal fans who travelled over to France had to wait until the 65th minute for their side's next opportunity.
Nicolas N'Koulou made a mess of trying to clear the Marseille area which allowed Walcott to fire in a low shot that was saved by the feet of home keeper Steve Mandanda.
And the Marseille stopper repeated the feat again when he blocked Van Persie's fiercer effort, with just a few minutes remaining.
The match was heading towards a forgettable draw until two minutes into stoppage time when Swiss defender Djourou swung the ball in from the right which Gervinho took the sting out of en route to Ramsey.
The midfielder, who replaced Andrey Arshavin, controlled the ball before firing past Mandanda.
Arsenal limited Marseille to one clear chance when Remy beat Per Mertesacker but his goalbound shot was deflected off course by the foot of Carl Jenkinson.