England and Bath winger Anthony Watson's season has been ended by an Achilles injury.
The 24-year-old was hurt during the first half of England's NatWest 6 Nations defeat to Ireland on Saturday.
"Anthony has been in superb form this year, and we're obviously really disappointed to have lost him at a critical part of the season," director of rugby Todd Blackadder told bathrugby.com.
Watson, who has scored 15 tries in 33 Tests for England, was driven off the pitch on a buggy in the 34th minute at Twickenham.
England head coach Eddie Jones said post-match that Watson had suffered an Achilles injury which was "not good" and the player's club have confirmed the severity of the problem.
Watson, who underwent rehabilitation work on another Achilles injury last year, had only just displaced Mike Brown for the number 15 shirt and the injury is a blow to England, who travel to South Africa in the summer.
It will also deny Bath a key man for their Aviva Premiership run-in.
Ireland have secured the NatWest 6 Nations Grand Slam by beating England 24-15 at TwickenhamRead the full story ›
England have dropped George Ford and moved Owen Farrell to fly-half for their NatWest 6 Nations clash with Ireland at Twickenham.
Dylan Hartley has recovered from a tight calf to lead the team in Saturday's final round of the Championship, but his front row colleague Dan Cole has been replaced by Kyle Sinckler.
Eddie Jones has performed significant surgery on the team that lost 22-16 to France, with Danny Care and Joe Launchbury making way for Richard Wigglesworth and George Kruis.
Anthony Watson retains his place at full-back with Mike Brown confined to the bench for another week.
There is a new-look midfield partnership of Ben Te'o and Jonathan Joseph, who returns at outside centre, and Elliot Daly has recovered from his foot problem to start on the left wing.
Injuries to Nathan Hughes and Courtney Lawes see Sam Simmonds and James Haskell start at number eight and openside flanker.
England's defence of their Six Nations title has ended in failure following a 22-16 loss in France.
Ireland had moved to the brink of glory by claiming a 28-8 bonus-point win over Scotland in Dublin earlier today.
Eddie Jones' side headed into their game knowing they needed to match Ireland's result against Scotland to keep the championship alive, but defeat at the Stade de France handed the NatWest 6 Nations crown to Joe Schmidt's men.
To get more reaction and highlights from the 6 Nations head to our dedicated site here
England must explain the tunnel fracas involving Owen Farrell at Murrayfield on Saturday following a request for clarification by Six Nations Rugby.
The Rugby Football Union and its Scottish counterparts have been asked to provide their accounts of the scuffle that took place shortly before Eddie Jones' men were defeated 25-13 in a pulsating Calcutta Cup match.
Television footage appears to show a clash between Farrell, England's inside centre, and Scotland number eight Ryan Wilson that ended when they were pulled apart by team-mates.
The incident unfolded as the players left the pitch and entered the tunnel upon completion of their warm-ups.
For more news and highlights visit our dedicated NatWest 6 Nations site: www.itv.com/six-nations
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