Champions League - Ramsey snatches Arsenal win
After a largely dispiriting 90 minutes in which both sides struggled to create clear-cut chances, substitute Ramsey controlled an accidental flick-on from Gervinho and placed his shot low past Steve Mandanda to give Arsene Wenger's side a fifth win in six games in all competitions.
The result sees Arsenal go top of the group on seven points, while Marseille - who have won only once in 10 league games this season - drop to second with six points. Arsenal may now only need to win one of their final three games to progress to the knockout stages.
The Gunners - looking to shake off their own poor start to the domestic season - were somewhat ragged in the first half at Stade Velodrome, with Alex Song demonstrating as much after only four minutes when he was caught in possession by Andre Ayew and then chopped down Loic Remy to earn himself a booking.
In a game of few chances, referee Damir Skomina ducked a number of big decisions. After 14 minutes, though, he was perhaps correct to avoid giving the home side a penalty when the ball struck Carl Jenkinson on the side, despite Marseille's players appealing for a penalty, so vehemently in Ayew's case that he was booked.
Marseille could have conceded a spot-kick of their own when Souleymane Diawara leapt to meet a corner from Mikel Arteta and saw the ball strike his arm. When it popped up into the air and Benoit Cheyrou failed to clear, Robin van Persie's looping header was then cleared off the line by Diawara.
Arsenal were struggling to find fluency in the final third, as they have done for much of a testing season, and when Andre Santos exchanged passes with Van Persie and then Tomas Rosicky, the Czech midfielder failed to find the Brazilian as he threatened to break through on goal.
Marseille had a touch more guile in the shape of their front three of Ayew, Mathieu Valbuena and Remy, and the third of the trio did superbly well after 31 minutes to keep the ball in play, nutmeg Per Mertesacker and see his shot deflect off Jenkinson and wide of the far post.
Lucho Gonzalez, a transfer target for Arsenal in August, then got his toe to a clever cross from Valbuena but the half ended with another talking point for the match officials as Santos, already booked for a bodycheck on Valbuena, committed a blatant handball but was not booked.
Arsenal lost Jenkinson to injury just after the hour mark as he was replaced by Johan Djourou. With Kieran Gibbs and Bacary Sagna already on the sidelines, the blow left Arsenal's full-back ranks even further depleted.
Whether due to selection issues or general incompetence, the Gunners have struggled for consistency at the back all season and looked vulnerable once again when a dinked cross from Remy fell to Gonzalez. Mertesacker helped ensure he was unable to get a shot away before Song almost gifted Marseille a goal with some sloppy play as he attempted to run the ball clear.
Arsenal enjoyed a rare chance in an insipid second half on 64 minutes. Walcott nipped in ahead of Nicolas N'Koulou as the defender slipped, but he recovered with a desperate challenge that did enough to prevent Walcott from beating Mandanda from close range.
With the game apparently petering out to a disappointing 0-0 draw, Van Persie suddenly sprung to life as he collected a pass from Gervinho and forced Mandanda into a block at his near post.
But as Marseille employed a rather negative approach despite their home advantage, the Stade Velodrome was silenced with seconds remaining of the tie when a cross from Djourou was turned into the path of Ramsey, who converted for his second goal in two games.
Though far from their best, Arsenal kept a clean sheet for the first time in 18 Champions League away fixtures and took top spot in the group with an important win.