Wales and Cardiff Blues flanker Sam Warburton is expected to be sidelined for six weeks after suffering a knee injury.

Warburton suffered a medial ligament strain during Cardiff’s 24-24 draw against Ulster in their Guinness Pro12 clash in Belfast last week.

Head coach Danny Wilson confirmed Warburton's absence, but does not envisage any problems with regard to his availability for this summer's British and Irish Lions tour to New Zealand.

Warburton, who captained the Lions in Australia four years ago, is the bookmakers' favourite to skipper them in New Zealand.

Lions head coach Warren Gatland announces his Lions tour squad next Wednesday, while the Lions leave for New Zealand on 29 May, with the first Test taking place in Auckland on 24 June.  

Warburton, who has won 74 Wales caps and is regarded as European international rugby's leading openside flanker, will be key to the Lions' Test series hopes.

The Lions have not claimed a Test series triumph in New Zealand since 1971. 

Speaking at a Cardiff Blues press conference on Tuesday, Wilson said: "Sam has a low grade medial strain which will put him out for approximately six weeks, which won't interfere with the Lions.

"He shouldn't have any problem regarding the Lions.

"Knowing how diligent Sam will be, with all these things, you see players who get back quickly if they follow religiously the protocol and they get a bit of luck.

"And I am sure that will be the case with Sam in terms of him following the protocol, and then we will see, all being well, how quickly he can come back.

"'Low grade' was the important bit of news.

"Sam is very experienced and a good professional who knows his body. He knows if he works hard he will be back relatively quickly.

"I think it is relatively good news, considering how it could have been."

Wilson, meanwhile, did not rule out Warburton being fit if the Blues are involved in the Champions Cup qualification play-off final, which takes places during the final weekend in May.

Two Pro12 teams, one from the Premiership and a French Top 14 club, face semi-finals on 20-21 May, with the final taking place the following weekend.