Didier Drogba was taken to hospital after suffering a horrific head injury in Chelsea's 3-1 win over 10-man Norwich on Saturday.
Drogba was knocked out in a collision with Norwich goalkeeper John Ruddy and was carried off on a stretcher wearing what appeared to be a breathing aid after receiving treatment for seven minutes at Stamford Bridge.
Blues boss Andre Villas-Boas revealed Drogba had remained unconscious "for quite some time" and he confirmed the 33-year-old had been taken to hospital for further examination.
"We are just waiting for the full exams on his concussion and hopefully nothing is wrong," Villas-Boas said.
"He is showing some good signs of recovery for us to be a little bit more tranquil."
Villas-Boas cleared Ruddy of any blame for the challenge, but admitted he had been shocked by the incident.
"It looked pretty nasty. He lost consciousness completely on the pitch," Villas-Boas said.
"I have to be very, very grateful, not only to my players but to the Norwich players and to my medical staff for reacting so quickly to a potentially dangerous situation."© ANP/AFP