Ospreys centre JJ Engelbrecht could be out of action for up to eight weeks with an ankle injury.
The former South Africa international limped off after 10 minutes of Ospreys 30-22 defeat by Connacht.
He joined the Welsh region in January from Japan Top League side Toyota Industries Shuttles.
Hooker Matthew Dwyer will also be out for six to eight weeks after injuring an ankle playing for the Army against Worcester.
"We've discussed the management of JJ's with specialists and will continue to observe his injury as he works towards a return to playing within eight weeks," said Ospreys medical manager Chris Towers.
Englebrecht's contract runs until the end of this season.