Manchester United defender Phil Jones saw his World Cup hopes thrown into doubt after suffering a suspected dislocated shoulder in his side's Premier League clash with Hull City.
The 22-year-old was replaced just 18 minutes into his side's 3-1 victory over Steve Bruce's side after going down following a heavy aerial collision with Maynor Figueroa after trying to get on the end of Adnan Januzaj's corner.
England manager Roy Hodgson has previously identified Jones as a guaranteed member of his 23 man squad providing he steered clear of injury, but his participation in Brazil in now in serious jeopardy after being taken to hospital with his arm in a sling.
"He's gone to hospital and we will just have to assess it," United's interim manager Ryan Giggs told the club's website following their final home game of the season. "But it does not look great.
"I'm just saying that the reaction, he asked to come off straight away, whether it's precaution or not, from a player's point of view, you don't know if it's bad. Hopefully it's not too bad."
Jones, whose United career has been disrupted by injury, has been utilised in a variety of positions across the pitch since his arrival in 2011 but has frequently been deployed in his favoured position at centre half alongside Chris Smalling this term.
The United duo were assured of their places on the plane to Brazil by Hodgson earlier this year. "We wouldn't be taking more than four centre backs with us to Brazil," the England boss said, speaking before February's friendly with Denmark.
"I don't think any country would. Jagielka, Cahill, Jones and Smalling – they are our four."
Cardiff City captain Steven Caulker, who was called to the England squad for that friendly earlier this year, would be in contention to replace Jones along with Everton youngster John Stones.
Arsenal and Tottenham Hotspur wingers Theo Walcott and Andros Townsend are confirmed absentees from this summer's finals along with Southampton forward Jay Rodriguez.
Hodgson will name his 23-man squad on Monday 12 May.