Substitute Aaron Ramsey’s stoppage time winner puts Arsenal top of Group F after overcoming a toothless Marseille at the Stade Velodrome.
A tight first-half was followed by a one-sided second period, The Gunners pounced on the French’s side’s insistence to play for a point.
The Welshman’s second Arsenal goal in as many games leaves Arsene Wenger’s side top of their group, and in pole position to qualify for the last 16 in a season littered with problems on and off the field.
Despite going into the game having endured their worst start to a Barclays Premier League season, Arsenal had reason to be optimistic when traveling to unbeaten Marseille, who had won just one of their opening 10 league games, while Wenger's side had never lost away from home to French opposition in the Champions League
In an early going dominated by petty cautions, both sides were unlucky not to be awarded a penalty with Carl Jenkinson handling Andre Ayew’s cross, and Souleymane Diawara misjudging Mikel Arteta’s corner, which led to Robin Van Persie’s header being cleared off the line.
The home side continued to probe for the remainder of the first half, but a combination of a miserly, if not nervy visitors defence, coupled with the wastefulness of Loic Remy and then Lucho Gonzalez kept the scores level at the break.
It wasn’t until with half an hour remaining that Arsenal sparked into life, firstly Van Persie’s snapped effort was comfortably saved by Steve Mandanda, before the Frenchman’s left foot denied Theo Walcott.
But in the final stages, as Marseille’s threat wavered, Arsenal struck in stoppage time as Johan Djourou’s cross went all the way through to Ramsey, whose cool finish sees Arsene Wenger’s side top Group F.