Mark Hughes has admitted that he is worried about Bojan after the Spaniard went off injured in Stoke City's 4-1 FA Cup win over Rochdale at Spotland on Monday.
Bojan opened the scoring with a wonder-goal on four minutes, but his night turned sour shortly after the half-hour mark when he was substituted due to a suspected knee injury.
"There is a concern there for us," the Potters boss told Sky Sports News.
"We don't know how bad it is. He has gone back home and we will check him in the morning. He is due for a scan so hopefully he will be okay.
"Hopefully if the scan is clear he will be okay and it is just a short-term thing but at the moment it's a concern for us."
Stephen Ireland, who replaced the former Barcelona starlet, added a second on 52 minutes, before Victor Moses struck a third on the hour mark.
Rhys Bennett reduced the arrears after 78 minutes, but Jonathan Walters was on hand to re-establish the three-goal cushion late on.
Hughes's side travel away to Blackburn Rovers in the fifth round.
