Marseille do not begin their European campaign until later this month, but their coach Élie Baup had likened Sunday night's Ligue 1 showdown with Monaco at the Stade Vélodrome to a Champions League game and the outcome was something of a reality check for his team.
OM's performances in August had been encouraging, with Marseille winning their first three league games for only the sixth time in their history - although last season they won their first six matches, something no club had done since Monaco in 1960.
However, those wins came against newly-promoted Guingamp and against limited opponents in Evian-Thonon-Gaillard and Valenciennes, so Sunday's game against Claudio Ranieri's Monaco was the first proper test for this Marseille side.
"Monaco is a massive test, a huge match. Playing them is a substantial challenge for any team. It is like a Champions League game," Baup had said beforehand, as supporters looked forward to renewing a rivalry that had fallen by the wayside during Monaco's two-year stay in Ligue 2.
It is a rivalry that reached its peak in the early 1990s, when the two regularly fought for the title, with Marseille invariably coming out on top.
Indeed, nobody old enough will have forgotten about Basile Boli's elbow on Juergen Klinsmann that left the German out cold on the Vélodrome turf in a game that OM won 1-0 against Arsène Wenger's Monaco in 1992.
On this occasion, with the visitors losing the pivotal Jérémy Toulalan to injury inside ten minutes, Marseille were the better team in the first half and deservedly led at the interval. Brazilian defender Lucas Mendes - himself only on the field because of an injury to Souleymane Diawara - headed home a Mathieu Valbuena corner and the 45,000 home fans erupted.
Under Baup, Marseille's relative success has been built on a sound defence and scoring the opening goal is usually the guarantee of a good result - they had not lost any of their last 30 Ligue 1 games in which they had taken the lead since March 2012.
But, inexplicably, that previously solid defence went to sleep in the second half, allowing Monaco to equalise through Radamel Falcao's third Ligue 1 goal and then clinch a 2-1 win when debutant João Moutinho sent through early-season revelation Emmanuel Rivière to finish past goalkeeper Steve Mandanda.
"Our first-half performance was interesting, but we lacked concentration at the start of the second half," said Baup, whose team nevertheless go into the international break in second place and, crucially to their fans, sit a point clear of bitter rivals Paris Saint-Germain.
As a result, there is no need to be despondent, but even this early in the season Marseille could scarcely afford to lose such a match if they did indeed have designs on the title. Instead, another top-three finish remains the realistic aim.
"There is no need to worry for OM, whose good first-half showing should not be forgotten," wrote Régis Testelin in L'Equipe. "But we now appear to be on for the two-horse race between PSG and Monaco that many had predicted."
The principality club are off to their best start to a season since the introduction of three points for a win in 1994, and winning at the Vélodrome sets them up nicely for their next away outing, at the Parc des Princes on September 22. Meanwhile, Marseille's thoughts begin to turn towards the Champions League proper.
The draw could hardly have been crueller on them as, despite being among the second seeds, they found themselves in Group F with Arsenal, Borussia Dortmund and Napoli. Amid such competition, Marseille are the underdogs and will be doing very well indeed even to finish third.
"In the eyes of everyone, we are the little team in the group, and that is sort of true," said OM sporting director Jose Anigo. "Let's just enjoy the fact that we are there," remarked club president Vincent Labrune.
Despite that, with Giannelli Imbula looking like a considerable upgrade on Joey Barton in central midfield and the signings of Dimitri Payet and Saber Khalifa strengthening the attack even before a protracted deal to sign France under-20 World Cup star Florian Thauvin from Lille had been completed, Marseille should still be tough opposition as long as their defence maintains its concentration. Their next big test comes in a little over two weeks time, when Wenger comes back to the Vélodrome with Arsenal.