Castres crushed La Rochelle 67-20, while there were also Top 14 wins for Montpellier, Toulon, Racing, Toulouse, Brive and Clermont.
Heading into this round, Castres sat just outside the top-six playoff zone, but their 10-try thumping of La Rochelle, coupled with Bordeaux’s defeat to Montpellier lifted Castres into a playoff qualifier spot.
Flyhalf Benjamín Urdapilleta put in a Man of the Match shift for the winners and contributed 22 points via a try, seven conversions and a penalty.
The hosts made a strong start and scored three tries, including one from scrumhalf Rory Kockott, to lead 22-3 at the break.
Both teams scored twice in quick succession after the restart, despite La Rochelle being reduced to 14 men. But from there, Castres pulled away. They ran in five unanswered tries in the final quarter to round off the result.
With just two rounds remaining, the rest of the top five teams all stayed on course for the knockout stage of the competition with victories, but there was one positional switch among them, with Toulon replacing Montpellier in second place, which earns automatic qualification for the semi-finals.
Montpellier snatched a 19-16 victory over Bordeaux thanks to a late try by hooker Bismarck du Plessis. Earlier Demetri Catrakilis had kicked four penalties that saw them trail 16-12 in the dying stages, before Du Plessis broke Bordeaux’s resilience to hand his team the win.
Elsewhere, wing James O’Connor bagged four tries as Toulon hammered Agen 52-13, Johan Goosen scored 18 points in Racing’s 43-13 demolition of Pau, Toulouse defeated Oyonnax 25-17 and Brive cruised to a 45-25 win over Grenoble.
On Sunday, log leaders Clermont claimed an emphatic 36-10 triumph over Stade Français, with scrumhalf Morgan Parra contributing 23 points with a try, three conversions and four penalties.
Round 24 results:
Castres 67 La Rochelle 20
Montpellier 19 Bordeaux 16
Toulon 52 Agen 13
Racing 43 Pau 13
Toulouse 25 Oyonnax 17
Brive 45 Grenoble 25
Clermont 36 Stade Français
Photo: Remy Gabalda/Getty Images