Conor Murray has been told by Warren Gatland he must get some game time under his belt if he is to join the British and Irish Lions on their tour to New Zealand.
Ireland scrum-half Murray was named in Gatland's 41-man squad on Wednesday but is still struggling with a neck problem sustained in the Six Nations defeat to Wales on March 10.
While Gatland is confident Murray can overcome the issue before the Lions depart in June, he wants the Munster man to prove his fitness before then.
"He's going to need to play before he gets on the plane," said Gatland. "That's going to be important for us.
"I would be reluctant to take someone to New Zealand with a neck injury who hasn't played. His last game was against Wales, on March 10.
"He's got a nerve issue. He had a setback a couple of weeks ago.
"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's going to be OK.
"He's had some disc problems in the past, but that's not what's causing the issue. It's some nerve problem that he's got.
"It's a concern, because he is a quality player. I think he's disappointed himself. He was hoping to be right this week for Munster. So hopefully he's going to be right in a couple of weeks and get one or two games under his belt."
Rhys Webb and Ben Youngs are the other scrum-halves in Gatland's squad.