England and Bath flanker Sam Underhill is set to miss the Six Nations after having ankle surgery.
The 22-year-old was injured during Bath’s victory over Leicester on 30 December and is expected to be out for up to three months.
That would see him miss the tournament, which starts on Friday 1 February and ends on Saturday 16 March.
England travel to Dublin to face Ireland in their first match on 2 February (kick-off 16:45 GMT).
Underhill was part of England’s 2018 Six Nations side and featured in three of the autumn internationals.
In better news for England, Saracens’ Maro Itoje, as expected, has returned to action in time for the start of this season’s Six Nations.
The 24-year-old second row has not played since chipping his kneecap during the autumn internationals.
“It was a weird one because I could run, I could jump, I could do everything I needed to do – with pain,” he said.
“I was able to flex my quad, so all the markers you would test for injury, I passed them all. There was still a little bit of discomfort, then it eased, then it came back again.
“On the whole it was feeling relatively good but it just wasn’t getting any better so we had to have a deeper look at it and the results came up.”
BBC rugby union correspondent Chris Jones
After an injury-plagued first season in England, Underhill came of age in the recent autumn internationals, with an outstanding individual performance against the All Blacks.
But his ankle problem means he will likely now miss the whole of the Championship. While Eddie Jones will be buoyed by the return to fitness of Tom Curry, England will miss Underhill’s physicality and abrasion – especially on the opening weekend in Dublin.