Munster have the fate of their Champions Cup future in their own hands ahead of next weekends final round of games.
The Reds took a losing bonus point from their clash with Racing in Paris, with two late penalties for the home side giving them a 34-30 win.
Castres are the visitors to Thomond Park next weekend where a win of any kind will see the Reds into the last eight, although they could have to travel in the next round.
