London - Wales back Liam Williams is set to miss the Six Nations games against Ireland and France this month after struggling to recover from an ankle injury, defence coach Byron Hayward said on Tuesday.
The Saracens star has not played since suffering the problem during training before the World Cup semi-final against South Africa last year.
Wales, who started their Six Nations defence with a 42-0 victory against Italy, face Ireland in Dublin on Saturday. They have not tasted victory there in the Six Nations since 2012.
"Liam's struggling a bit at the moment," said Hayward. "It (Saturday's game) is a little bit early for Liam. We are possibly looking at the fourth or fifth games in the championship.
"Leigh Halfpenny had a great game last weekend at full-back, though it would be nice to get Liam back."
According to Hayward's timescale, Williams could be considered for the match against England on March 7 and the final game against Scotland the following week.
While Williams remains sidelined, Wales centre Owen Watkin, scrum-half Gareth Davies and hooker Elliot Dee are all back in training following recent injuries.
Wales head coach Wayne Pivac is due to name his starting line-up on Thursday for the Ireland game, with reports that Saracens centre Nick Tompkins will be handed a first Test start.
The 24-year-old excelled as a second-half replacement against Italy, scoring a brilliant solo try as Wales crushed the Azzurri.
If Tompkins is promoted off the bench, it would seem likely that George North would revert to his familiar wing position from outside centre.
"Nick made an impact and certainly put his hand up for selection," Hayward said. "He took to the international stage like he had been there for many years. He applied himself in training and is very knowledgeable."