Toulon edge Toulouse
All their points came from penalties as star-studded Toulon struggled to find a way to break down the Toulouse defence despite dominating possession.
The win leaves Toulouse in fifth place on 61 points, three points clear of Castres and eight better off than Bordeaux who tackle Stade Francais later Saturday.
Only the top six sides qualify for the playoffs.
"We have had our lot of frustrations this season," said Ugo Mola, the coach of 19-time French champions Toulouse.
"This time we are happy with our four points.
"Our scrum allowed us to take the fight to Toulon. But that was not the only thing – our scrum, our defence and our kicking game.
"Florian Fritz was a hero this afternoon."
Toulon backline coach Steve Meehan blamed a series of mistakes for the deposed European champions' defeat even though they remain in third place, five points behind Montpellier.
"We were not disciplined enough and gave away too many penalties especially when we were under pressure," said Meehan.
"And yet we started well and I told the players at half-time that if we continue to play like that we would score tries.
"We have four games left before the playoffs and we have time to put things right but we will have to work hard."
Toulon had by far the better of the first half but after 40 minutes all they had to show for it was a penalty from flyhalf Eric Escande against six points from the boot of his Toulouse counterpart Sebastien Bezy.
Centre Fritz took over the kicking duties and strikes from him after 58 and 69 minutes moved Toulouse 12-3 clear with the home crowd voicing their disapproval of their team.
Toulon brought on powerhouse centre Mathieu Bastareaud in a last-ditch attempt to break down the Toulouse defence and they finally crossed the try line in the last minute, South African flank Juan Smith providing the finishing touches.
They had one last possession to pull off what would have been an undeserved win, but Australian wing James O'Connor was bundled into touch on the halfway line.
Elsewhere, Montpellier, managed by South African World Cup winning coach Jake White, eased to a 10th successive win in all competitions with a 51-10 rout of Grenoble.
They ran in seven tries to ease to a bonus-point win which gave them a five-point lead over Toulon in the table.
