Wales back George North faces an anxious wait to see whether he will be fit for a third British and Irish Lions tour after suffering a leg injury for Ospreys against Cardiff Blues.
North suffered the problem early in the second half of the opening Pro14 Rainbow Cup 36-14 victory.
The 29-year-old played an important role in Wales' 2021 Six Nations title success, featuring at centre.
Lions coach Warren Gatland names his squad to face South Africa on 6 May.
North appeared to get his leg stuck in the Liberty Stadium turf and was in notable pain before being helped off the field.
He was featuring on the wing for his region after being used as a centre by Wales coach Wayne Pivac this season.
North's versatility makes him a prime candidate - if fit - to be named in Gatland's 36-man squad to tour South Africa in July and August.
"You always worry when people get injured when no-one is near them," said Ospreys head coach Toby Booth.
"That doesn't normally bode well for anybody so that makes it sound like it's structural. I know you are going to ask me how bad it is but I don't know.
"The next 48 hours are crucial in relation to assessment and management. We've got a very good medical team with a lot of experience.
"We'll know over the next few days when it settles and we get some images in to confirm what we are actually dealing with.
"It would be an enormous blow for him (if it was a lengthy lay-off), it would be devastating.
"He's got back to the top of his game and been one of the standout players, showing he can play at both centre and wing.
"That multi-positional player is great for any squad. We wish him well and we'll look after him and we'll get the information to start the process."
Booth outlined how North was after the game in the changing room.
"We meet as a team afterwards and he was there," said Booth.
"Obviously he's got his crutches and this next 48 hours planned out for him. He's a bit sombre as any player would be when he gets injured.
"Unfortunately we understand that's part and parcel of being a professional rugby player.
"He knows we need to find out what we are dealing with and then we can make a plan from there."