Racing 92 claimed the last remaining play-off spot in the Top 14 on Saturday, while Clermont Auvergne edged out leaders La Rochelle to qualify directly for the semi-finals.
Defending champions Racing headed into the final round of the regular season with their position in sixth under significant threat due to the congested nature of the table, with only five points separating them from Bordeaux-Begles in 11th.
However, nearest rivals Stade Francais, Pau and Lyon were all beaten as Racing squeezed past Bordeaux 22-20 at Stade Yves du Manoir - Dan Carter scoring a try, two conversions and a penalty - to make sure of a play-off berth.
Racing will now face Montpellier, whose 27-26 victory over Stade was not enough to lift them into second as Clermont beat La Rochelle 30-26. Stade almost ran out winners at Altrad Stadium, only for Francois Steyn to miss a conversion with the last kick of the game.
The other play-off will see Toulon - 32-12 winners against Pau - host Castres, whose season ended with a 33-27 loss at Brive.
Relegated Grenoble bowed out of the top flight in style with a 53-21 thrashing of Lyon.
Saturday's other fixture saw 12th-placed Toulouse beat rock-bottom Bayonne 40-12.