Ma'a Nonu scored a crucial late try as Toulon pulled off a 27-20 victory at previously high-flying La Rochelle on Sunday.
Earlier, Toulouse gained a third straight bonus-point victory as they beat Brive 45-28 to climb up to third in the French Top 14.
La Rochelle out-scored Toulon by three tries to two but still ended the game empty handed as Toulon fly-half Anthony Belleau -- playing for his club after he was banned from the French national team for one game for his role in the infamous late-night drinking incident in Edinburgh -- kicked a late penalty to deny the hosts even a losing bonus.
New Zealand international Tawera Kerr-Barlow gave La Rochelle the lead with the opening try on 19 minutes.
Pierre Bourgarit and Pierre Aguillon also crossed the whitewash in the first half but Englishman Ryan Lamb could convert only one of the three tries.
Jonathan Wisniewski had kicked three penalties for Toulon and South African JP Pietersen's try meant they turned around at the break trailing only 17-14.
Lamb scored La Rochelle's only points of the second period with a penalty but Belleau kept Toulon in touch with a kick from the tee of his own.
Former All Black Nonu crossed to give Toulon the lead with Belleau converting and then adding a late penalty to take the losing bonus point away from La Rochelle.
Toulon are fourth, a point behind Toulouse, while La Rochelle dropped from third to sixth.
Toulouse gained the bonus point that took them above Toulon two minutes after the regulation 80 had expired.
Having regained possession in the last seconds deep in their own half, Toulouse moved 80 metres up the field before scoring with a penalty try after Petrus Hauman deliberately knocked the ball out of play to stop Yoann Huget touching down.
"We did what we had to do," said Ugo Mola, the Toulouse coach. "But I would have liked us to make the match a lot easier. The big black mark is still the 28 points (conceded) at home."
Toulouse took the lead in the second minute with a try by winger Cheslin Kolbe. The other winger, Huget, added a second after 13 minutes while Zack Holmes touched down after half an hour.
Toulouse also struck twice early in the second half with tries by Huget and Maxime Medard.
Yet every time the home team seemed to have their hands on the bonus point -- for scoring three more tries than the opposition -- Brive hit back with Julien Ledevedec, Samuel Marques and, finally, Sevanaia Galala touched down to set up the last-play drama.
Brive, meanwhile, suffered their third consecutive defeat and dropped to 13th in the table -- a relegation playoff position.
Montpellier opened up a six point lead at the top with a nail-biting 11-10 win over Bordeaux-Begles on Saturday, while second-placed Racing 92 lost 24-15 at Pau.