British and Irish Lions head coach Warren Gatland explained that Johnny Sexton must prove his fitness during the Six Nations to stake his claim for the Lions number 10 jersey.
Sexton will not play in Ireland's opening game against Scotland on Saturday as he is still struggling with a calf injury. It's bad news for the player who would surely be a shoo-in to start at fly-half for the Lions on their tour to New Zealand later this year.
Gatland says that he needs players who keep their fitness for the month-long tour and Sexton will need to get a healthy dose of game time during the Six Nations.
"Someone of Johnny's experience and calibre, you hope he is going to get back fit and get a number of games under his belt, potentially in the Six Nations and towards the end of the season," Gatland told The Independent.
"He is a really quality player but there is going to be some real attrition in New Zealand and you are going to need players who are going to be able to handle what is going to be an incredibly tough and physical tour with the 10 matches.
"Hopefully we have a group of players that can last that time and you don't pick up too many injuries. That's something that we have got to be aware of.
"The next few months are important for him. It's not just Johnny, there are a number of players from the four nations who have had injuries and have found it difficult to put a consecutive part of the season together.
"Johnny has been unfortunate in the last couple of seasons in that he has picked up a few injuries, a couple of knocks to the head as well, so I'm hoping that he gets back to fitness as quickly as possible and starts to play in that Irish team and performs well."