Darren McGregor will have a scan on Monday to discover the extent of a knee injury suffered during St Mirren’s weekend defeat to Hibernian.
The defender, who missed the majority of the last campaign with a cruciate ligament injury, is feared to have suffered the same fate in his other knee.
McGregor was stretchered off during Saturday’s game and his manager, Danny Lennon, fears he could be set for another lengthy spell on the sidelines.
"It is not looking too good for Darren and he is very distraught after fighting back from a cruciate knee injury last season," said Lennon.
"Although it is too early to say, it looks like he has done the other knee but we have a fantastic medical team here and he is a great character so I'm sure he will come through this again.
"He’s a character who can get through it. We’ll need to wait until we get the diagnosis but we fear the worst.
"I spoke to Darren in the treatment area after the game and he’s distraught. He wears his heart on his sleeve and will show you every emotion.
"We have a fantastic medical team and Darren is a great character who’ll be supported by the other lads. We’ll see him through it whatever the diagnosis."
McGregor, 27, missed seven months of the 2011/12 season after injuring his knee during a match at Dundee United in August last year.
He made his return in March 2012 and played a further six games, regaining his regular spot in Lennon’s side for the new season.