Brian O’Driscoll knows exactly what Sean O’Brien has to do to make the Lions squad

We would had presumed Sean O'Brien to be a certainty to make the British & Irish Lions squad.

Not so, according to a host a rugby fans, pundits and former players. Warren Gatland names his Lions squad in London on April 19 and there will be some big names left very disappointed on the day. Gatland is expected to take about 40 players to New Zealand and nine of them should be back-rowers. Gatland has tried to remain coy on who he will pick but, over various interviews he has mentioned 13 players:

Owen Farrell, Jonathan Joseph, Stuart Hogg, Jamie Roberts, Sam Warburton, Rory Best, Robbie Henshaw, Garry Ringrose, Owen Farrell, Conor Murray, Johnny Sexton, Alun Wyn Jones and Tadhg Furlong.

Gatland has also admitted that paring down the back row selections will be his toughest task. The common consensus is that Billy Vunipola, Justin Tipuric, Maro Itoje and CJ Stander will join Warburton, leaving four places up for grabs. O'Brien toured with the Lions to Australia in 2013, playing in two Tests, and is said to be a favourite of both Gatland and Ireland/Lions defence coach Andy Farrell. Still, former Lions captain Brian O'Driscoll is not sure his former Leinster and Ireland teammate is guaranteed to go. He told Rugby Tonight:

"One guy that needs a huge game [for Leinster] this weekend is Sean O'Brien. "He has been a little bit quiet in the Six Nations. I know that Gats and Andy Farrell like him but he could really do with a massive game this weekend."

Funnily enough, a huge Champions Cup performance is exactly what Ronan O'Gara predicted could sway Lions selection for Munster captain Peter O'Mahony. O'Gara told The Hard Yards:

"The key game for him will be at Thomond Park against Toulouse. If he comes up with another man of the match performance - and timing is everything - he's going to be, at least, on the plane."

Two men. Two big games. Surely they both can't go... can they?