Lions coach Warren Gatland says Ireland scrum-half Conor Murray must play a game for Munster to make the tour of New Zealand this summer.
The 27-year-old has been sidelined since sustaining a neck/shoulder injury against Wales last month.
Gatland named Murray in his squad on Wednesday but revealed the player had suffered a setback in his recovery.
"He's going to need to play before he gets on the plane - that's important for us," said Gatland.
Gatland added that Murray has met with a neurologist over a nerve issue and is ruled out of Munster's European Champions Cup semi-final against Saracens on Saturday.
Munster also have a maximum of four Pro12 games remaining for Murray to get back in action.
"He's got a nerve issue and it is a concern. I spoke to the doctor. He was hoping to be fit this week but he had a setback a couple of weeks ago," said Gatland.
"I would be reluctant to take someone to New Zealand with a neck injury who hasn't played.
"He's incredibly fit. It's causing him a bit of discomfort and a bit of weakness in his arm, and hopefully he's going to be right in a couple of weeks - the neurologist is confident he is going to be okay."
|June 3 - Provincial Union Team, Whangarei|
|June 7 - Blues, Auckland|
|June 10 - Crusaders, Christchurch|
|June 13 - Highlanders, Dunedin|
|June 17 - Maori All Blacks, Rotorua|
|June 20 - Chiefs, Hamilton|
|June 24 - All Blacks, Auckland|
|June 27 - Hurricanes, Wellington|
|July 1 - All Blacks, Wellington|
|July 8 - All Blacks, Auckland|