Celtic left-back Greg Taylor was substituted before half-time through injury during the pre-season friendly with Ross County at Parkhead.
A late challenge from new Staggies man Connor Randall had Taylor needing treatment during the first half.
The left-back tried to continue, coming back onto the park after receiving the attention of club physios.
But Taylor then went down twice more before manager Neil Lennon decided it was time to replace him.
Youngster Kerr McInroy came on to replace him in the 44th minute but now Celtic will be concerned regarding their depth at left-back.
Boli Bolingoli has served as back-up to Taylor throughout pre-season but he wasn't in Sunday's matchday squad.
Jonny Hayes, who previously filled in at left-back or left-wing-back, was let go at the end of last season to rejoin Aberdeen.
