Injury adds to insults for French outcast Thomas
Thomas hobbled off after 52 minutes, forced to watch from the sidelines as the 2016 champions slumped to a 15-24 loss.
Thomas was one of eight players exiled from the France squad for going on a night out after losing 26-32 to Scotland in Edinburgh earlier this month.
He had scored three tries for France in the first two games of the Six Nations.
All Blacks legend Dan Carter also left Saturday's game early having popped over just one penalty.
Carter, winding down his French career, was replaced by veteran flyhalf Albert Vulivuli and the change at least brought a degree of joy for Racing whose two tries both came after the World Cup winner's 64th-minute departure.
Racing stay in second place in the table but are now 11 points behind Montpellier who edged Bordeaux 11-10.