Celtic's on-loan winger Patrick Roberts could be missing for up to three months with a hamstring injury.
The 20-year-old had to be replaced during the first half of Celtic's 1-1 draw with Motherwell.
He has now returned to his parent club, Manchester City, for further tests.
Celtic manager Brendan Rodgers expects Roberts to be out for several months, but is hopeful that Moussa Dembele will be fit for Tuesday's Champions League game against Anderlecht.
"Patrick is going to be out for a period of time," Rodgers told BBC Scotland.
"It could be anything up to three months. He is going back down the road to Manchester City to have another scan on it.
"It is just unfortunate. We will wait for the scan result but he will certainly be out for the foreseeable future."