It may still be only a matter of time before Paris Saint-Germain plant their flag at the Ligue 1 summit, and leave it there for good, but Marseille's determined performance in the 2-2 draw between the sides demonstrates that they're not going to have everything their own way.
Sunday night's match seemed to provide the perfect stage for PSG. It was the first time in 18 years that the two rivals had gone into a league fixture against each other while occupying the top two positions in the table, and PSG knew that victory would take them above their opponents into first place for the first time since they relinquished top spot to Montpellier in March last season.
PSG had won their previous four games in Ligue 1, scoring 10 goals for the loss of just one, and seemed to be growing in power and belief (albeit despite a 1-0 loss to Porto in the Champions League). Marseille, in contrast, had seen their run of six straight wins come to a juddering halt in an abject 4-1 defeat at Valenciennes. "The match will enable us to judge ourselves and to find out whether we're capable of beating everyone in the league," said PSG right-back Christophe Jallet.
However, instead of the anticipated accession, PSG found themselves hustled out of their stride by a Marseille team superior in terms of application and commitment, and who might have taken all three points had it not been for two typically imperial contributions from Zlatan Ibrahimović.
As in all the great rivalries, much of Marseille's sense of identity is derived from their fierce opposition to everything PSG, and the events of the last year or so have only served to make the distinction between the clubs clearer. If PSG are the nouveau riche aristocrats, OM have become the sooty-faced street urchins, scrapping and scheming for everything they can get. In André-Pierre Gignac, the striker no-one wanted, who matched Ibrahimović's brace at Stade Vélodrome, they have a fittingly unglamorous figurehead for their resistance to the billionaires from Paris.
Having a player like Ibrahimović means PSG go into every game with a get-out-of-jail-free card, but the starkness of their 'Ibra-dependence' against OM demonstrated the extent to which they remain a work in progress. Remove his two stunning strikes, and you're left with a curiously listless display not dissimilar to the performance that saw PSG go down 3-0 on the same pitch 11 months previously. Once again, Javier Pastore seemed cowed by the hostility of the Vélodrome, and was removed at half-time. Commentating on the game for Canal+, Christophe Dugarry could scarcely hide his amazement at how static the visitors were in possession.
There are also issues concerning Carlo Ancelotti's tactics. You could be forgiven for forgetting that this is the man who once managed to crowbar no less than four playmakers - Clarence Seedorf, Rui Costa, Kaká and Andrea Pirlo - into the same team at Milan, such is his fondness for predominantly conservative midfielders. PSG lined up with three of them (Marco Verratti, Blaise Matuidi and Clement Chantôme) in a narrow system against Marseille, as in almost every other league game this season, and finished the match with no less than four full-backs on the pitch after Gregory van der Wiel and Sylvain Armand came on in the second half.
Formations are, of course, neutral, and the 4-3-1-2 has been adopted to get the best out of both Pastore and Ibrahimović, but in such a defensive league, and with so many attacking players at his disposal, does Ancelotti really need three players in front of his back four?
There is an expectation in France that PSG's victory in this season's title race is a mere formality. "At the least, they'll be between 10 and 15 points ahead of the team in second place. They're unplayable, as we were at one time," Lyon presidential advisor Bernard Lacombe told L'Équipe last week.
A sketch on Les Guignols de l'info, meanwhile, imagined an alternative version of the FIFA 13 video game, in which selecting PSG automatically guarantees victory without the need to even play a match. "You have chosen to play with Zlatan," says a voice in the game. "No, I wanted PSG," responds the bewildered gamer. "PSG is Zlatan," comes the reply.
The events of Sunday night suggest that might not actually be too far from the truth, but as long as Ancelotti remains dependent on his Swedish talisman to haul PSG out of trouble, Ligue 1 fans can at least enjoy the suspense.
Follow Tom Williams on Twitter @tomwfootball