Chelsea will have to wait before finding out exactly what is wrong with Oscar.
The Brazilian playmaker was clattered by Arsenal goalkeeper David Ospina in the first half of their 0-0 draw at the Emirates Stadium on Sunday.
Oscar was taken to hospital after being replaced by Didier Drogba at half-time but Mourinho was unaware of the extent of the injury straight after the match.
"He went to hospital at half-time. I don't know (if it is concussion), we are waiting," he said.