Wales prop Samson Lee will undergo surgery on a full rupture of his Achilles tendon, putting his Rugby World Cup hopes in doubt.
The talented tighthead suffered the injury in last Saturday's Six Nations win over Ireland.
Lee is expected to be out for six months after his procedure next week, with Gatland describing his chances as "50-50". "It's going to be long-term – could potentially keep him out of the World Cup," Gatland told reporters.
Gatland also added that Adam Jones would have been under consideration for a call-up had he not retired from Test rugby earlier this year.