Started off well with good saves from Jack Wilshere, and even an unorthodox one against Kieran Gibbs. Solid, but should have done better with Ramsey's game-settler.
Replaced Souleymane Diawara in the line-up recently, and the Brazilian's performances continue to impress Elie Baup. A threat from set-pieces, defensively he was sound too.
The Cameroon defender has been inconsistent this season, and that continued tonight too. Aerially, he was beaten at set-pieces, and committed a few unnecessary fouls. Was opened up by Ramsey for the second goal too.
A poor evening from Morel, who it could be argued, gave the game away for L'OM. A poor header towards Walcott, who volleyed in the opener, it was all downhill for the hosts from that point.
The right-back was a powerful presence on the wing, routinely getting down the flanks to provide deliveries.Should have really opened the scoring after a poor finish straight after half-time.
The tricky winger looked a real threat in the opening stages, but just couldn't finish his chances when it counted. Opened up the Gunners on occasions, but his passing was on point.
Preferred to the much more experienced Benoit Cheyrou - the Ligue 2 Player of the Year excelled in the middle of the park, venturing forward and linking well with the attackers.
Inexperienced at this level, the Togo international was efficient and effective in a blistering first 45 minutes for OM. Tailed off in the second.
Intriguing tussle with Aaron Ramsey throughout the 90 minutes, but in truth, it was a mixed night for Ayew, who despite getting into good positions, failed to make it count. Until the last minute, but his penalty award was a soft one.
The big striker was a threat for the Arsenal defenders to deal with at the back, but like Valbuena, his profligacy ensured OM went the night empty-handed. Had a golden opportunity to score.
Payet had been criticised for slacking off in OM's two previous games, but the France international was a bright spark tonight. Showed good pace and trickery on the flanks, and tested Szczesny with a couple of good strikes from distance.
A good evening from the Poland international, who despite a minor blip concerning Mertesacker, denied Marseille with some good saves. Couldn't do much about the penalty.
Marshalled the likes of Gignac well, but almost scuppered Arsenal's game plan with a stunning deflection behind, for Gibbs to clear off the line. Decent, but not his best.
The France international improved from his performance at the weekend, and was instrumental in limiting Marseille's attacking ventures.
The right-back struggled initially up against Payet, but nevertheless did well to become more of a threat in a great spell in the second half.
A strong performance from the young full-back. Up against a powerhouse in Rod Fanni, the Englishman held his own well and frustrated his opponent.
The Germany international displayed some decent football in linking up with the wingers. Highlight for him, was firing wide after being set through by Gibbs. Not a goal threat, but the summer signing is going from strength to strength.
Back in his hometown and former club, Flamini struggled with his composure in the first half against an improving Marseille in the 1st half. Rallied in the second to limit OM's creativity.
Good evening from Wilshere, whose calm nature in possession and good movement off the ball became more apparent in the second half. Saw a good effort beaten away by Mandanda.
Scorer against OM here in 2011, Ramsey achieved the feat once more with a well-taken second. Across the midfield, he was instrumental in leading Arsenal from their malaise after a tussle with Ayew. Perhaps unlucky in conceding a penalty.
Walcott bagged his first goal - a well-taken volley after a defensive howler from Jeremy Morel, and generally enjoyed a good outing at the Velodrome. Good passing, and a threat out wide.
An off night for the France international. Struggled up against the superb Lucas Mendes, he didn't really get onto anything his team-mates put on for him.