Newcastle striker Aleksandar Mitrovic has apologised to the club's doctor after having to be restrained as he tried to return to the pitch following a head injury.

The 21-year-old Serbia international was knocked unconscious minutes after scoring his side's equaliser in the 1-1 draw with Sunderland at St James' Park on Sunday.

Quoted in a Serbian newspaper, Mitrovic said: "I didn't know what the procedure was. I didn't know the rules.

"I apologised to the doctor after the game because I knew I had to come off after being knocked unconscious for a few seconds. I've been through the examinations, my head is fine."