Five minutes later Marseille had scored again thanks to a superb goal from Thauvin as he smashed a shot high into the net on his left foot to make it 2-0.
There was no way back after that for Rennes, who have now gone 10 league games without a win.
Lille eased their relegation fears with a 1-0 win at fellow strugglers Caen in their first game under new coach Franck Passi.
They had defender Adama Soumaoro sent off just after the hour mark but Anwar El Ghazi, a January signing from Ajax, struck the only goal of the game with 20 minutes left.
Giant Malian striker Cheick Diabate’s late penalty secured a 1-1 draw for Metz at home to Nantes and Angers beat Nancy 1-0.