British and Irish Lions 2013: Sam Warburton knee injury is worse than first thought

If it has been a funny old season for Sam Warburton, it is getting less funny by the minute. Missing the opening game of a British and Irish Lions tour through injury is no laughing matter, especially for a captain desperate to reinforce his leadership credentials by performing strongly in the opening weeks of the trip. Missing it through something as potentially serious as ligament damage is enough to make a grown man cry.

According to the Lions head coach, Warren Gatland, who has asked the Irish lock Paul O'Connell to skipper the side against the Barbarians tomorrow, Warburton has been struggling for 10 days and is not expected to train again for another five – a timescale that puts his participation in the first game on Australian territory, in Perth next Wednesday, under serious threat. Should the Welsh flanker be ruled out of that contest with Western Force, he will have an awful lot of ground to make up.

Like every coach under the sun, Gatland's first instinct was to play down the issue. "Sam wanted to turn out against the Baa-Baas, but it is so early in the tour we felt it wasn't worth the risk," he said. "The last thing we want to do is get through the next three or four weeks and then come into the Test phase and not have him fit and available."

But he then confessed that Warburton had damaged his medial cruciate ligament – something very different to the "bump on the knee" diagnosis trotted out initially. Ears pricked up immediately. Knee injuries are two a penny in modern rugby, but any mention of the L-word sets the alarm bells ringing.

Gatland's thought process in turning to O'Connell was neither long nor hard. "It was a no-brainer – a very obvious decision to make in terms of his leadership experience and the respect he commands," the coach said. Indeed, it could not have been easier. Blessed with rich experience of guiding the Lions through the rugby minefields of the southern hemisphere, the man from Limerick has been in prime form for Munster after recovering from a long-term back problem.

"This is a big privilege," O'Connell said. "The guys have just completely dived into this whole thing – we are already a very tight group – and there's such a big buzz about the tour and the potential for making something really special of it. There are a few of us here who have toured with the Lions before and not been successful, and it isn't the greatest feeling. Those who do know what it is to win with the Lions are different from the rest of us, so it's a question of us trying to join them."

As expected, Gatland's first selection features players who have been in camp for the duration, rather than those who joined up late after playing in domestic and European club finals. Eleven of the team will be starting a Lions game for the first time, the exceptions being the centre Jamie Roberts, the scrum-half Mike Phillips, the prop Adam Jones and O'Connell himself.

"We've always said that everyone will get a start in the first three matches: the great thing is that there is so much competition for places and we want to ensure that the maximum number of people feel they can put up their hand for a Test spot if they play well," the coach said. "Those in this team have an opportunity to set a mark and put some pressure on the others, but we won't even start thinking about the make-up of the Test team until the first four games are behind us."

Despite Gatland's best intentions, some players may reach Queensland next weekend without having had a show. Two Irishmen, the full-back Rob Kearney and the flanker Sean O'Brien, are struggling with hamstring and knee problems respectively, while the Welsh prop Gethin Jenkins has a calf strain.