Scott Murray, who led Scotland in Australia early this summer, will miss his country's difficult autumn Test programme which includes visits by the Wallabies and South Africa.
The Edinburgh lock pulled up during a Scotland training session on Monday and has undergone keyhole surgery to repair the damage on an injured left knee joint but will not be fit in time for the Tests. The Scots face Australia on November 6 and Japan a week later before meeting Australia again at Hampden Park and South Africa at Murrayfield.
The hooker Gordon Bulloch will be favourite to take over from Murray, who replaced Chris Paterson as captain after last season's Six Nations whitewash.
Scotland's coach Matt Williams said: "It's very disappointing to lose Scott for the autumn to a non-contact injury. It's obviously unfortunate but we do have some depth at lock after the progress made on tour by the likes of Alastair Kellock, Craig Hamilton and Scott Macleod."
Leicester's fly-half Andy Goode faces six weeks on the sidelines with a knee injury. Goode, the Premiership's top scorer this season with 50 points from three appearances, damaged ligaments during Tigers' 39-22 victory over London Irish last Sunday.
Apart from potentially missing four Premiership games the injury threatens Goode's participation in the club's opening Heineken Cup appointments with Calvisano and Biarritz. Leicester's 19-year-old prospect Ross Broadfoot looks likely to deputise in the East Midlands derby against Northampton on Saturday.
A rib injury rules Wasps' captain Lawrence Dallaglio out of Sunday's visit by London Irish.
The South Africa full-back Percy Montgomery has agreed a three-year contract extension at Newport Gwent Dragons.
Ian Swan, who won 17 caps for Scotland between 1953 and 1958, has died at the age of 74. The wing played club rugby for the Army, London Scottish, Leicester and Coventry.
· Japan will bid for the 2011 World Cup. "Until now the World Cup has been held in countries from the Six Nations or Tri-Nations. We think, and the International Rugby Board thinks, that it is time for rugby to go global," said Japan's Rugby Football Union secretary Koji Tokumasu.
