Gary Cahill’s hopes of forcing his way into Fabio Capello’s World Cup plans were dashed yesterday when the Bolton Wanderers defender was all but ruled out for the rest of the season with a blood clot in his left arm.

Cahill had complained of tightness on Thursday only for it to have swollen to such an extent by Saturday morning that he was admitted to intensive care for emergency treatment, only hours before Bolton were due to play Fulham at the Reebok Stadium.

Doctors at the Royal Bolton Hospital diagnosed a blood clot and administered anticoagulant drugs to address the problem. Cahill is thought to have been transferred to a private clinic and was due to be released last night, although his condition is being monitored carefully.

“I think, given what I’m being led to believe regarding the medication and everything else, I, as a manager, will not be taking a risk with Gary’s welfare and wellbeing,” Owen Coyle, the Bolton manager, said. “I would be delighted if he comes back [this season], but in terms of percentages, I am not holding out much hope.”

Cahill’s absence will come as a huge blow to Bolton’s hopes of avoiding relegation, and Capello, the England manager, may be equally dismayed that question marks hang over the availability and physical condition of yet another centre half with the World Cup finals in South Africa only four months away.

The 24-year-old was called up to the England squad for the World Cup qualifying match against Kazakhstan in Almaty last June as cover for Rio Ferdinand, the Manchester United defender.

But while Cahill has yet to play for his country at senior level, he stood an outside chance of making Capello’s final 23, particularly given the problems the Italian has at centre half.

Despite replacing John Terry as England captain last week, Ferdinand was out of action for three months this season with a back problem that remains a source of serious concern and Ledley King and Jonathan Woodgate, the Tottenham Hotspur defenders, are perennially injured.

Phil Jagielka, the Everton defender, has yet to play this season because of a ruptured anterior cruciate ligament, Joleon Lescott, of Manchester City, has been out for the past eight weeks with a knee problem and Matthew Upson, the West Ham United centre half, has not been without injuries of his own this term.

“I thought that if he kept playing to the level that he was then he’d have been in the World Cup squad,” Coyle said. “Having seen the quality of players England have — and they do have quality in that position — then Gary wouldn’t be out of place. There is no doubt about that, but it looks as if that will now pass him by.”

Cahill’s condition is not entirely dissimilar to that suffered by John O’Shea, the United and Ireland defender, who was ruled out for the remainder of the season last month by his club manager, Alex Ferguson, after a blood clot in his thigh became knotted. Signed from Aston Villa by Gary Megson, Coyle’s predecessor as Bolton manager, for £5 million in January 2008, Cahill has gradually grown in stature, drawing plaudits not only for his courage and composure in defence but his ability to score goals.

Cahill is his team’s top scorer this season with seven goals and his presence at both ends of the field is certain to be greatly missed by Bolton, who are only a point — and a place — above the relegation zone.

In his absence, Coyle will have to rely on Zat Knight and Andy O’Brien, who will be charged with keeping Manchester City at bay when Bolton travel to Eastlands this evening. “You are always disappointed when you lose one of your best players,” Coyle said. “You want them available all the time. When they are not available, though, you go with the ones you have and you look for them to do their best.”

From Villan to hero

• Gary Cahill made 31 appearances in 3.5 years for Aston Villa, having joined the club as a trainee, before leaving for Bolton Wanderers for £5 million in January 2008. His time at Villa also included loan spells at Burnley and Sheffield United.

• He has made 78 appearances and scored ten goals during his two years at Bolton and is the club’s top scorer this season with seven goals.

• Cahill represented England at under-20 and under-21 level, but despite being called into the senior squad for the World Cup qualifier away to Kazakhstan last June, he has yet to win a full cap.