Didier Deschamps has admitted that Toulouse deserved to beat his stuttering Marseille side.
Aymen Abdennour bagged the only goal of the game at the Stade Velodrome, which meant Les Phocéens have now gone without a win in their last four games.
Deschamps said that his players' performance "was not up to scratch" in a game they simply had to win.
"We didn't really show up. It's a shame to have lost but I can't say I'm really disappointed. Toulouse deserved their win; they played a compact game with a lot of aggression," said the 42-year-old.
"There were too many things going against us to expect to have won. We had players in international action in mid-week, who only resumed training yesterday, and we had some important players unavailable.
"Collectively, our performance just wasn't up to scratch. There are still a good number of games left in the season, but we need to start taking points. We had to win tonight, and we didn't."
Defeat means that Marseille are now eight points adrift of the Champions League places.