Outside half Rhys Patchell had booted the blues into a 9-6 lead but they were reduced to 14 men on 25 minutes when Wales scrum half Williams was sent off for a dangerous tackle.

And Montpellier took full advantage of their extra man with tries from Yoan Audrin, Mamuka Gorgodze and Timoci Nagusa.

The victory sees the French club climb to second in the group while the Blues' European hopes are in tatters.

Having thrown victory away against Sale in Round One and succumbed to a narrow defeat at the hands of Toulon the following week, the Blues needed a victory to keep their slim hopes of advancement alive.

But they went into the must win clash without a host of stars, including Wales trio Bradley Davies, Jamie Roberts, Leigh Halfpenny and Sam Warburton.

And it did not take long for the French club to make their numerical advantage count, with quick hands releasing Audrin in the left hand corner.

Paillaugue converted and continued to exchange penalties with Patchell as the Blues entered the break trailing by four points.

They quickly reduced the deficit to a single-point but Montpellier hit-back with a second try.

Paillaugue and Santiago Fernandez combined to make the initial inroads and Audrin almost crossed the whitewash for a second time but the ball was recycled and Gorgodze drove over from close-range.

Montpellier failed to add the extras and Patchell responded with his seventh penalty but the diminutive French scrum-half put the result beyond doubt.