Sam Warburton’s selection as British and Irish Lions captain was thrown into serious doubt on Tuesday after Cardiff Blues revealed the flanker would miss the next six weeks with a knee injury.

The former Wales captain, who was replaced by fellow Lions candidate Alun Wyn Jones as skipper before the Six Nations, limped out of the Blues’ Pro12 game with Ulster on April 7, with the region since confirming it is a medial knee injury.

Warburton is expected to be out of the rest of the domestic season but he is still thought to be fit in time for the tour to New Zealand in June.

British and Irish Lions captain candidates Show all 6 1 /6 British and Irish Lions captain candidates British and Irish Lions captain candidates Alun Wyn Jones Jones is probably still the leading candidate for the captaincy, even if his, and Wales’, Six Nations was not what they were hoping for. Jones took the Welsh armband from Sam Warburton for the championship but at times looked uneasy at making a call, such as when he was overruled when Wales opted to go for the corner against Scotland, rather than taking the shot at three points. Jones captained the Lions in the deciding third Test against Australia in 2013 and is a guaranteed starter if fit – something Gatland is keen for his captain to be, although not a necessity. AFP/Getty Images British and Irish Lions captain candidates Sam Warburton Had Wales not finished fifth in the championship with three defeats, there is a good chance Warburton would have been named player of the tournament. The way he reacted to losing the Wales captaincy and moving to blindside flanker has been phenomenal and he is now the bookies’ favourite after his performances and having already led the Lions to a tour victory. Of Warburton’s chances, Gatland said: “He's a different captain to some other players. He leads by example. He doesn't say a lot but he has had that experience. He's one of the guys potentially in contention, definitely.” However, he has been so good without the burden of the armband, would giving it to him hinder his performances? Getty Images British and Irish Lions captain candidates Dylan Hartley Before his red card for Northampton in December, Hartley was the frontrunner for the armband but now his place on the plane is not even assured. For England, Jamie George has impressed and could usurp his captain’s position over the next 12 months, with Hartley arguably not even the third most impressive Hooker the home nations boasted during this year’s Six Nations. However, his grit and fire has been one of the reasons for England’s success under Eddie Jones and it is that sort of personality which could be vital in the hotbed of New Zealand. Getty Images British and Irish Lions captain candidates Rory Best The way Best led Ireland to ending England’s unbeaten run shows that he has the ability to motivate the players around him in tough and gritty situations. He has also captained a side to a win over the All Blacks, the only candidate who is able to say that. Best is certainly a viable candidate but the question mark that remains hanging over him is if he is good enough to start at hooker against the All Blacks? Hartley, Best, George and Wales’ Ken Owens are all in with a shout. AFP/Getty Images British and Irish Lions captain candidates Owen Farrell Farrell was player of the tournament after a stunning Six Nations. His kicking is up there with Leigh Halfpenny’s as amongst the best in the world and he has the right mentality of a captain having been schooled under Eddie Jones. Farrell looks certain to start at 12 for the Lions and would make a fierce captain. However, having not captained an international side from the start, how would he fare leading the most intense tour the Lions have embarked on? It is a tough challenge for the most weathered of captains, never mind a novice. AFP/Getty Images British and Irish Lions captain candidates Conor Murray An outside shout for captain but the way he controls the game from around the ruck shows his importance to the Lions. He, like Best, has experience of beating the All Blacks and of a winning Lions Tour (like everyone on this list, other than Hartley). He has captaincy experience but while he was a certain starter a month ago, the performances of Rhys Webb have given Gatland a real decision to make. He said he wants to pick his squad first and then his captain and that could go against Murray in the decision-making process if Webb is now considered ahead of him. Getty

However, confirming the news, Blues coach Danny Wilson revealed that he hoped the 28-year-old would be available for the Champions Cup play-off final on May 26th, three days before the Lions depart for New Zealand.

“Sam has a low grade medial strain which will put him out for approximately six weeks,” he said.

“It won’t interfere with the Lions.

“If we were fortunate enough to make the second European play-off game, we would envisage him being available for that.

“So he shouldn’t have any problems regarding the Lions.

“You see players who get back quickly if they follow protocol through religiously and get a bit of luck and I am sure that will be the case with Sam, knowing how diligent he will be.

“We will see then, all being well, how quickly he can get back.

“It was low grade and that was the important bit.

“Sam is very experienced and a good pro. He knows his body and knows if he works hard to get that right he will be back relatively quickly.

“He has been fine today. I think it’s relatively good news considering how it could have been.”

Warburton returned to his best form during the Six Nations which shot him to the front of the queue for the captaincy, despite changing position from openside flanker to blindside.

Warburton injured himself playing for Cardiff Blues (Getty)

Head coach Warren Gatland names his tour party of April 19th, with Warburton expected to be named as captain for the second consecutive tour although the injury could put that in doubt.