Lawrence Dallaglio's chances of returning as England captain for the match against the Barbarians at the end of the month and next month's tour of Argentina have receded, with the Wasps No8 confirming last night that he may need swift surgery on his left thumb.

Dallaglio damaged a ligament in the thumb in the win over Harlequins 10 days ago and played with it strapped against Northampton last Saturday. He will see a specialist this week and there are now serious doubts whether he will lead England for the first time since stepping down after lurid drug allegations in 1999.

"I will be guided by the doctor," he said. "It's his call and I'm told that if I need surgery it could take 10 weeks to mend. All I know is that this time whatever decision is made on my fitness will be the right one."

When Dallaglio injured knee ligaments at Loftus Road 12 months ago he went on the Lions tour a month later and did not recover to play in the Tests. Instead, subsequent knee surgery meant that he returned for club duty only six weeks ago, but in five Premiership starts since then Wasps have won five games to put themselves on the threshold of a place in the Heineken Cup. "It's ironic really because in my career I've been pretty much injury-free but after nine months [out], and without playing any second-team rugby, I came back and was playing catch-up. I felt fitter and faster than ever but then I fielded a loose ball against Quins, collided with someone and damaged the thumb.

"I injured the right thumb in exactly the same way in 1993. The injury is commonly called skier's thumb so I know the score by now. I am still hoping to play against Bath on Sunday but I will be guided by the advice of the specialist from now on.

"I've spoken to Clive Woodward [the England manager] and he's been understanding about it but I can't rush back if I'm not fully fit." The loss of Dallaglio would be a blow to Woodward, whose two captains in the Six Nations, the Leicester forwards Martin Johnson and Neil Back, are both unavailable for the trip to South America next month, when England will play one Test against the Pumas.

The scrum-halves Kyran Bracken and Matt Dawson, both former England captains, could step into Dallaglio's boots, and the Leicester lock Ben Kay is another candidate. With Dallaglio's 30th birthday approaching this summer, England will also want their No8 fully fit to help lead their tilt at the World Cup next year.