Greater Manchester Police have confirmed they will investigate Ben Thatcher's challenge on Pedro Mendes during Wednesday night's Premiership match between Manchester City and Portsmouth at the City of Manchester Stadium.
Football Association officials are looking at their own regulations for punishing players to see if further action can be taken against Thatcher, who has since written to Mendes to apologise .
The Manchester City full-back crashed into the Portuguese midfielder in the second half of the goalless draw at Eastlands. The Portsmouth player was knocked unconscious and spent the night in hospital.
'We are looking at whether this may possibly be an exceptional case and what options may exist under our disciplinary regulations,' an FA spokesman said.
Greater Manchester Police confirmed Thatcher could also be interviewed by police if Mendes decides to pursue the matter with a formal complaint.
A spokeswoman said today: 'Greater Manchester Police has received a number of complaints from members of the public following an incident in which a player was injured during the Manchester City v Portsmouth match on Wednesday 23 August 2006.
'Officers will now be liaising with the injured player, the clubs and the Football Association to review this matter and determine if any further action is required.'
Referee Dermot Gallagher gave Thatcher a yellow card for the challenge, meaning the 30-year-old defender should escape further sanctions under strict disciplinary guidelines.
The tackle, which sent 27-year-old Mendes into the advertising hoardings, was condemned by Pompey boss Harry Redknapp and later by television pundits who examined the forearm challenge.
'The FA have to do something,' said the Portsmouth manager. 'It is there for all to see. I do not want to see anyone suspended but how could that possibly not be a red card? What do you have to do to get a red, kill someone?'
Mendes has left hospital and will travel back to Portsmouth with club officials.
'He will continue to be under medical and neurological supervision during the forthcoming week,' read a statement on official Portsmouth website.
Officers will now speak to Mendes, both clubs and the Football Association to decide what action to take - which could result in the Premiership player being charged with assault.
The City defender has previously been punished for elbowing Sunderland's Nicky Summerbee in 2000, for which he received a two-game ban, and may now find himself in hot water again following his latest indiscretion.
Manchester City have made no comment on the matter so far, and it is not known whether Thatcher will face any internal disciplinary action from his own club.