The 25-year-old suffered the injury while in Heineken Cup action with the Cardiff Blues against Exeter Chiefs and having undergone surgery on Tuesday, he is expected to be out of action until June.
Priestland played a key role in securing Wales a third Six Nations Grand Slam in eight years earlier this year and featured in all four of the Red Dragons’ autumn internationals, most recently in the 14-12 defeat to Australia.
And Scarlets head coach Simon Easterby has tipped Priestland to bounce back even stronger from the injury.
“It’s a big blow for Rhys and for our region to lose a player of his quality and influence in our team,” said Easterby.
“He was coming through well in the last couple of games of the autumn, put in a strong performance against Australia and was making a real impact in our game against Exeter – so it’s very difficult for him to take; but he’ll get plenty of support from here throughout the injury period.
“I am sure that a player of his experience, intelligence and ability will deal with this very well and after a couple of weeks away to recover from the surgery will be back and can be a very positive influence in our environment.
“He’s a committed Scarlet and a player with a very good rugby brain and there will be a lot he can do to work in and around our environment to help the team, some of our younger players and in our preparations for games during rest of the season.
“We all want to show him as much support as we can right now, it’s going to be a tough few weeks for him to accept what’s happened but the boys here are a very close-knit group so I’m sure that will be a positive for him.”
And Scarlets head of medical Andy Walker revealed the surgery had passed off well.
“The surgery was undertaken this morning at the Vale Hospital and has gone very well,” he said.
“We have been fortunate to have had the injury assessed and repaired surgically so promptly and by a very experienced ankle and foot specialist.
“The anticipated time off the field is around six months but it all depends on the individual and how his rehab goes in the interim.”
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BIOGRAPHY: Mohamed Salah