Super Rugby will be reduced from 15 sides to 14 in 2021, with the Tokyo-based Sunwolves bowing out at the end of the 2020 season.
Top 14 defending champion Castres closed the gap to the top two as it defeated basement side Perpignan 36-17.
Top 14 leader Toulouse moved six points clear with a 27-14 defeat of Montpellier as Stade Francais halted La Rochelle's four-match winning run.
Julian Savea has vowed it will be business as usual after being singled out for criticism in a bizarre rant from Toulon president Mourad Boudjellal.
Dan Carter expressed his excitement at the prospect of returning to Racing 92 but conceded it was tinged with sadness due to Pat Lambie's forced retirement.
Clermont Auvergne moved to the summit of Top14 by beating Bordeaux-Begles, while Perpignan won for the first time in its match.