Roberts had been a major doubt after needing several scans on the neck injury sustained in a clash with Scarlets wing Sean Lamont last weekend.

He sat out the 21-5 home defeat with Glasgow Warriors on medical advice but will return to full training ahead of the European opener against Harlequins on Saturday.

The trainee doctor admits he still has stiffness when moving his neck to the right but he expects to be fit for the Anglo-Welsh clash at the Cardiff City Stadium.

Roberts, 22, said: "I've had a couple of scans on my neck and the spinal surgeon has given me the all-clear.

"He advised me not to play this weekend but I will start contact work early this week and I will be fit for Harlequins.

"When it happened, I was massively worried and it was a scary moment because it felt quite serious.

"You hear all about the horrific neck injuries that players pick up in simple and innocuous tackles and I hardly slept last Saturday.

"I went to hospital straight after the game for an x-ray but I was still in absolute agony at seven o'clock on the Sunday morning - moving my neck was a joke and extremely painful.

"I hoped it wasn't a fracture and fortunately the scans showed it was just muscular. I'm very fortunate I'm okay and counting myself lucky."

Roberts' return to full fitness is a huge boost to Blues boss Dai Young who is already without influential quartet Gethin Jenkins, Martyn Williams, Xavier Rush and Ma'ama Molitika for the home tie with Quins.