And as many of Warren Gatland’s preliminary 45-man squad head for a medical assessment this week ahead of their intense training programme, Williams will wait before getting back into full swing ahead of the first training camp in Poland on July 2.

Prav Mathema, Welsh Rugby Union national medical performance manager said: “Shane will be three more weeks before he is fully integrated into the training programme, which means he should be up to speed by the time we go on that first camp in Poland.”

Gatland is set to name his final squad for the tournament on August 22 and there are a number of other players who will also have to prove their fitness before then.

Cardiff Blues wing Leigh Halfpenny is also aiming to get to the Spala camp as he continues his rehabilitation from a foot operation while Blues prop Gethin Jenkins and Exeter-bound prop Craig Mitchell are back in training following a toe operation and dislocated shoulder respectively.

Meanwhile, Scarlets hooker Ken Owens has joined the squad as training cover for Richard Hibbard, who will be out for 10 to 12 weeks after a shoulder operation.

Mathema added: “Leigh is doing well after a successful operation on his foot, he is six weeks down the line now and able to start lifting weights again and also hopes to be at Spala.

“Both Gethin and Craig are back in full training and Richard has been given a return to play time of 10 to 12 weeks, which makes it possible for him to be back to fitness by the end of August.”

Wales have three tough warm-up matches, kicking off against 2011 RBS 6 Nations winners England on August 6 before a return game at the Millennium Stadium a week later.

The team will then face Argentina in Cardiff on Saturday August 20 in their final game ahead of the tournament before the final squad flies to New Zealand on August 31.