Toulon ran in eight tries in a 59-13 demolition of Castres on Saturday to book their place in the French Top 14 play-offs for the seventh year running.
With leaders Montpellier already qualified for the play-offs, Toulon -- second on 73 points -- are also now guaranteed a place.
Toulouse, in third, and fourth-placed Racing 92 have 70 points apiece and are also well-placed for the end of season shake-up.
Josua Tuisova got the first of a pair of tries for Toulon after just five minutes, Facundo Isa (22), Ma'a Nonu (34) and then Mathieu Bastareaud touching down to give the hosts a convincing first-half lead.
Alby Mathewson (76), the league's top scorer Chris Ashton (79), and Raphael Lakafia (80+1) touched down late for Toulon.
On the scoresheet: Toulon's English winger Chris Ashton scores a try on Saturday