Manchester City will not find out the extent of Kevin De Bruyne's hamstring injury until later this week.
The Belgium international came off nine minutes from the end of City's 3-1 win at Swansea on Saturday which gave them their 10th win in succession since Pep Guardiola became manager.
De Bruyne pulled up clutching his hamstring and was replaced by Jesus Navas for the final stages of the game at the Liberty Stadium.
Sky sources understand the player underwent scans on Sunday but the full prognosis will not be known for a few days.
After Saturday's game, Guardiola said: "From the way he reacted, I think it's a muscular injury but I am not a doctor. I don't know how serious it is so we will travel back and then see what the doctor says.
"It's a pity as Kevin is an important player for us. That's why we have to have a big squad as everyone will help us."
City travel to Glasgow this week for their second Champions League group phase fixture against Scottish title holders Celtic.
Having won their first game 4-0 against German side Borussia Monchengladbach, they are looking to continue their 100 per cent record in their group ahead of a double header with Barcelona.
De Bruyne has featured in all bar one of City's games this season, scoring two goals against Manchester United and Bournemouth.