A much-changed Racing 92 scored three late tries to stop Toulouse claiming a bonus-point victory in Top 14.
It was a tough outing for La Rochelle at Montpellier, as Racing 92 defended resolutely in their Top 14 beating of Toulon.
Pro14 side the Scarlets released a statement saying they will look into claims that La Rochelle players were subjected to racial abuse.
Scarlets' first Champions Cup knockout clash since 2007 saw them beat La Rochelle to reach the semi-finals.
The Scarlets have shown they have the talent to win the European Champions Cup, according to former Wales international Shane Williams.
Montpellier ran in five tries to claim a bonus-point victory over Castres, maintaining their position as Top 14 leaders.
Victory over Stade Francais moved Racing 92 to within four points of Top 14 leaders Montpellier but Toulon slipped to defeat at Oyonnax.
Ben Botica ensured Oyonnax built on their win at Clermont with another victory that boosted their unlikely Top14 survival bid.
La Rochelle are a formidable force on home soil, but suffered a rare defeat at Stade Marcel-Deflandre as Toulon came from behind to win.