Ospreys prop Cai Griffiths is to undergo surgery and has been ruled out for the rest of the season.
Griffiths, 31, suffered an arm injury against Bath and scans have revealed the extent of the problem.
"Cai has suffered a ruptured bicep, with the area affected on the inside of his elbow," said Ospreys medical performance manager Chris Towers.
"He is having an operation, with the best case scenario being a four month rehabilitation period."
Griffiths, who returned to the region from London Welsh in 20014, is the second Ospreys forward to be ruled out for the rest of the season.
South African lock Rynier Bernardo is to undergo knee surgery after suffering an injury during Ospreys' LV= Cup defeat to Gloucester in January.