Williams – who lost his starting place during Wales’ nightmare RBS 6 Nations campaign – is set to line-up for the Blues in their crucial league clash with Scarlets on Saturday.

Blues are set to face Wasps in the Amlin Challenge Cup next month – but Williams has taunted the Premiership side by insisting the trip to Llanelli will be a tougher test.

“It’s probably going to be our toughest game of the year,” said Williams. “We are going to have to go up 20 to 30 per cent.

“The Magners is a lot more competitive than the Guinness is. It’s very set-piece dominated.

“They have obviously got big packs and like to get through a lot of kicking, relying on driving lineouts and scrums. In the Magners League teams like to throw the ball around.”

Elsewhere in the Celtic league, Ospreys travel to European champions Leinster on Friday night while Newport-Gwent Dragons entertain Edinburgh on Sunday evening.