Celtic manager Neil Lennon is hoping Gary Hooper did not suffer a broken leg during the 1-1 draw with Kilmarnock at Parkhead.
The Celtic striker was stretchered off before the break after clashing with Killie defender Frazer Wright and was replaced by Anthony Stokes.
With the former Scunthorpe player off, Celtic passed up on a series of good chances to take the lead before Killie striker Conor Sammon grabbed his 15th goal of the season in the 54th minute to give the visitors a shock lead.
Celtic defender Thomas Rogne scored his first goal for the club to level five minutes from the end, but the draw kept Celtic two points behind Clydesdale Bank Premier League leaders Rangers having played a game more. The Celtic boss is looking for better news about Hooper on Wednesday morning.
He said: "The early prognosis isn't good. It looks like ankle ligament damage. It is too early to say whether he will miss the game against Rangers, I wouldn't like to call it. I watched it again on the television and it looks like he's stretched his ligaments.
"There's a worry about his fibula but we'll get a scan. It's a huge blow because he is our leading goalscorer and if he had stayed on the scoreline could have been different."