Jack Wilshere's double means that Arsenal travel to Napoli's Stadio San Paolo home on December 11, knowing that a point will guarantee their presence in the knockout stages of the Champions League.
Indeed, as long as Arsenal do not lose by three goals, they will progress to the last 16.
It seems crazy that Arsenal have 12 points but are still not through., but Borussia Dortmund's defeat of Rafa Benitez's side has ensured Group F remains a tense affair.
There was a resilience and organisation to Arsenal that showed there is so much more to them than silky football.
Wilshere took his goals well, particularly an elegant first, but praise is also due to Mathieu Flamini in midfield.
Marseille's team-sheet, revealing a weakened line-up, had simply filled Arsenal with even more confidence, a belief shown so wonderfully by Wilshere after only 27 seconds.
If Arsenal's electric start shocked Marseille, the other surprise was that Arsene Wenger's team did not add to the scoreline until midway through the second period.
Wilshere gave them the perfect start. The latecomers were still streaming in, taking up their red seats, catching a glimpse of the splash of blue in the corner where Marseille fans were their usual demonstrative selves.
Even Arsenal's goal did not dampen their spirits. It began after Flamini, again an important influence, cleared up a Marseille attack. Per Mertesacker then stroked the ball towards Olivier Giroud, who had dropped into the Arsenal half.
The Frenchman laid the ball off first-time to Bacary Sagna, who released Wilshere down the right. Exploiting the early nerves of the left-back Jeremy Morel, Wilshere ran purposefully into the box.
Lucas Mendes, Marseille's left-sided centre-half, tried to close him down. Wilshere shaped to go right, twitching a shoulder, wrong-footing Mendes. Wilshere cut in and curled the ball with that productive left foot around Nicolas N'Koulou and the 'keeper Steve Mandanda.
Wilshere ran away, sucking his thumb, a salute to his young child, and then punching the corner-flag. Up in the smartest seats, Thierry Henry smiled his approval.
Down in the statistical zone, one group of number-crunchers timed Wilshere's goal at 27 seconds, the quickest by an Englishman in the Champions League, comfortably breaking Wayne Rooney's mark of one minute and five seconds against Bayern Munich in 2010.
Arsenal could have threatened more club records in the first half. They could have scored four or five. Wilshere, Mesut Ozil and Tomas Rosicky were interchanging constantly behind Giroud, their movement confusing Marseille.
The visitors were struggling to live with the intelligent movement of Wenger's side. Their coach, Elie Baup, had made a raft of changes, starting Benoit Cheyrou, Souleymane Diawara, Florian Thauvin, Rod Fanni and Mathieu Valbuena on the bench. It seemed a declaration of defeatism by a team who had not won a point in Group F.
The half could have deteriorated further for Marseille. Aaron Ramsey turned N'Koulou just outside the area, was caught by the centre-half, and fell inside.
The Spanish referee, Antonio Mateu Lahoz, wrongly deemed the offence inside the area and pointed to the spot. Justice did prevail when Ozil, taking far too short a run-up, failed to inject enough speed into the ball and Mandanda threw himself right to save.
It was a surprisingly lax kick by the German international, who looked suitably angry with himself. Still Arsenal wasted chances.
Wilshere sent Ozil through the middle and he was fouled on the edge of the Marseille area by Morel. Ramsey's free-kick failed to bypass the wall.
Fittingly, Wilshere, the man of the match, was first out of the tunnel for the second half, having given a few words of encouragement to the gathering players, but it was Ozil who was most involved as the new period began.
Baup started strengthening his side, sending on Valbuena and Thauvin 10 minutes after the restart.
A further bulletin came through of Dortmund's second goal from Jakub Blaszczykowski, but Arsenal calmed any nerves after 65 minutes.
Ramsey rolled the ball down the inside-right channel and Ozil flicked a pass across to Wilshere, who scored from close range.
Dortmund were now leading 3-1 but the equation looks straightforward for Arsenal in Naples. (© Daily Telegraph, London)