Ospreys and Wales hooker Richard Hibbard may miss the rest of the season with a recurrence of a knee injury.
The Neath man, 26, went off in the 23rd minute of the Ospreys' 27-19 derby win over the Scarlets on Friday.
"He is a tough cookie so it's quite serious, early indications aren't great," said Ospreys coach Sean Holley.
