British Lions: Hamstring forces Sam Warburton out

British and Irish Lions captain Sam Warburton could miss the start of next season after suffering a “significant” hamstring tear.

The Wales and Cardiff Blues flanker faces a lengthy spell out of the game following an injury he sustained during last Saturday’s second Test defeat against Australia in Melbourne.

He will miss this weekend’s series decider in Sydney – centre Brian O’Driscoll is favourite to replace him as skipper – with Sean O’Brien his likely deputy in the No 7 shirt.

Warburton suffered what the Lions have described as “a significant tear” in his left hamstring. He limped off 13 minutes from time at the Etihad Stadium.

He will remain with the squad – the Lions fly home tomorrow week – although it is understood that the 24-year-old could be sidelined until October.

Warburton said: “It is incredibly disappointing to be ruled out of the tour through injury as we head to Sydney for the deciding match. I wish the team all the best, and hope I can play some part in the build-up this week. I am confident that the boys can finish the job off and secure the series win.”

Lions head coach Warren Gatland is due to announce his starting line-up for Sydney tomorrow, and it would be a major surprise if 34-year-old O’Driscoll did not take the reins for what would be his ninth Lions Test spanning four tours. And in terms of the back-row rejigging that will now be required, O’Brien would appear to be in pole position for the No 7 shirt vacated by Warburton, packing down between Dan Lydiate and Jamie Heaslip.

Warburton stayed in Melbourne on Sunday to undergo a scan while the rest of the Lions squad headed for a couple of days’ rest and recuperation on Queensland’s Sunshine Coast. The Lions said in a statement that Warburton remained under the supervision of team doctor Eanna Falvey “to undergo a whole medical assessment”.

Warburton, despite being only 24, has enjoyed a glittering career, leading Wales to the World Cup semi-finals in 2011 and being part of successive RBS Six Nations title-winning teams. But injuries have also accompanied him, resurfacing again to prevent him appearing in what would have been the biggest game of his life.