England flanker Sam Underhill is unlikely to play any part in the Six Nations after his club Bath revealed he requires an ankle operation.

Underhill sustained the injury when coming on as a replacement in Sunday’s 35-34 defeat by Northampton and with no date given for his return, he looks set to miss the entire championship.

“Sam will undergo surgery to rectify a new ankle injury. There is no set timeframe on his recovery,” a Bath medical update said.

England are well stocked for back rows but losing Underhill is still a major blow for head coach Steve Borthwick.

After being overlooked for the World Cup squad in 2023, the 28-year-old re-established himself last year by starting throughout the Six Nations and in all three Tests on the summer tour to Japan and New Zealand.

An ankle issue sustained on tour required surgery, delaying his start to the new campaign and forcing him to sit out the opening two matches of the autumn against the All Blacks and Australia.

But he was restored at openside for the clashes with South Africa and Japan that closed out the campaign, scoring a try in each game and impressing with his overall play.

A veteran of 40 caps, Underhill brings physicality to England’s pack, especially in defence where he is among the game’s most destructive tacklers.

It is the latest injury setback for Borthwick, who looks set to be without wing Immanuel Feyi-Waboso for the entire tournament because of a dislocated shoulder, while full-back George Furbank is struggling with a broken arm.

Flanker Ollie Chessum is closing in on his comeback from a knee injury, however, while scrum-half Alex Mitchell has fully recovered from a neck problem.

Borthwick names his Six Nations squad on Tuesday and faces a tricky opener against Ireland in Dublin on February 1.