Clermont Auvergne hammered fellow title hopefuls La Rochelle, who had won 10 of their previous 11 matches.
Wasps won for only the second time since September with a fit-again Joe Launchbury back in the side.
Zebre were no match for Pro14 rivals Cheetahs on Sunday as the South African side eased to a bonus-point victory on the road.
Racing 92's win over Toulon will not have made pleasant viewing for France coach Jacques Brunel as Teddy Thomas was injured.
Munster moved top of Pro14's Conference A after capitalising on Glasgow Warriors' defeat to in-form Benetton Treviso.
Bath finished the game with 11 men as they suffered defeat to lowly Worcester Warriors in the 98th minute.
Saracens welcomed Billy Vunipola back for Friday's trip to Sale Sharks but he could not inspire them to Premiership victory.
Having not played since November 10 due to ongoing concussion issues, Leigh Halfpenny appears to be a doubt for Wales' Six Nations campaign.
England coach Eddie Jones has been given a boost ahead of the Six Nations, with Billy Vunipola and Joe Launchbury to return for their clubs.
Mark Wilson has signed a new four-year contract with Newcastle Falcons after some brilliant displays for England in November.