Celtic captain Scott Brown will undergo a scan after suffering a hamstring injury that could hamper his club's Champions League qualification efforts.
The midfielder was stretchered off after pulling up inside the first minute of 1-1 friendly draw with Rapid Vienna in Austria on Sunday.
Manager Ronny Deila told the club's official website: "He got an injury and we think it was his hamstring, but we don't know yet how severe the injury is.
"Hopefully it's not big and he will be back quickly. He will have a scan and we will see what happens."
Celtic begin the first of a potential three Champions League qualification ties against KR Reykjavik in Iceland on 15 July.