Police are investigating the cause of an injury that hospitalised one of Chelsea's stewards after the club's controversial defeat to Manchester United on Sunday.
A Stamford Bridge steward needed approximately 10 minutes' treatment by paramedics after falling to the floor during the Barclays Premier League game, with the Blues confirming he had hurt his knee.
The injury was sustained as United celebrated Javier Hernandez's winner in front of the Matthew Harding stand, home fans responding by hurling abuse and appearing to throw objects onto the field of play.
It was unclear whether the steward, who was taken to hospital, was hit but there were suggestions he may have been caught up in a surge towards the advertising hoardings. The matter was serious enough for the Metropolitan Police to launch a formal inquiry.
A spokeswoman said: "We are aware of an incident during yesterday's match at Stamford Bridge in which a steward was injured. An investigation has been launched into the incident and our inquiries continue."
It is understood officers were examining CCTV footage to work out how the steward was injured.
Metropolitan Police commissioner Bernard Hogan said: "My understanding is that there is a steward with an injury and it's not yet clear what caused that injury but we will look into it with the club. There should be CCTV.
"Obviously, there was some dispute at the end of the game, given it had been quite a controversial game. What we have to find out is if there was just one person involved or if there were any more. We will review the footage and talk to the clubs."
Chelsea launched their own internal investigation into the matter on Sunday night. "We are looking at reports of objects that may have been thrown or incidents around the steward taking a fall," a club spokesman said after the match.
"We are investigating all the incidents around that time. My information so far is that he [the steward] slipped and fell, may have hurt his knee, and was being treated by the side of the pitch. He's been taken to hospital."