England scrum-half Shaun Perry is a doubt for the start of the Six Nations after suffering a freak injury playing for his club Bristol on Sunday.
Perry lost his England place to Andy Gomarsall during the World Cup
The 29-year-old has had surgery to repair a fractured cartilage in his windpipe after taking a boot to the throat in the win over Harlequins.
Bristol believe that Perry, a member of England's World Cup squad, is likely to be out for "weeks, not months".
"I feel for Shaun, he has been superb for us," said head coach Richard Hill.
The injury will hinder Perry's chances of being included in the squad for England's Six Nations campaign, which starts against Wales at Twickenham on 2 February.
The former welder went to the World Cup in France as first-choice scrum-half but lost his place in the match-day 22 after being substituted at half-time of the 36-0 defeat by South Africa in the pool stages.
Perry, who joined Bristol from Coventry in 2005, finished Sunday's game after receiving treatment on the pitch but continued to feel discomfort in his throat.
After the match, Bristol's medical team diagnosed it was the same injury that team-mate Nathan Budgett picked up in the game against Cardiff last month.
"When Budge (Nathan Budgett) suffered his injury, none of us had even seen an injury of this type before," added Hill. "For a second player to get injured in the same way barely a month later beggars belief.
"Shaun returned from the World Cup and got straight back to work with Bristol. He has embraced his role as a senior player and I've had no hesitation naming him captain in Matt Salter's absence."
Bristol will not set a time-frame for Perry's likely return until a full assessment of the injury can be made.
It is the latest blow to have hit the Bristol squad in the wake of the Harlequins match.
England hopeful Dan Ward-Smith fractured his hand, while David Blaney was stretchered off in injury time with a suspected broken ankle.