The chairman of the Premier League Doctors' Group (PLDG) has told The Times that clubs could be sued by players if they fail to stick more closely to guidelines on concussion.
He said the PLDG had called for sanctions against managers who made players go back onto the pitch after a head injury and that clubs should be fined for failure to follow procedures.
The warning of legal action comes after former rugby player Cillian Willis sued for clinical negligence against Sale Sharks.
The club had allowed Willis, who has now retired, to play on after he suffered a head injury in a game three years ago.
PLDG chairman Dr Mark Gillett warned that such a legal action "could come" in football.
Gillett said managers under pressure to win games "do need to be responsible to their players -- but it's asking a lot in our 'must win, must perform' situation to almost think logically about that."
"We need to find a way where it's taken out of their hands," he added.
"The only way to make sure that it's policed properly is to make sure the team is not penalised in terms of numbers. A fourth sub would certainly be helpful.
"Sanctions would come if a player is proved to be knocked out and they haven't taken them off the pitch, then the club is fined. That type of measure would be helpful."
Last year, the Football Association released new guidelines saying players who suffer a concussion should not return to games for 19 days at the earliest.
The recommendations also say any player suspected to have suffered a concussion should be immediately removed from action for the rest of a game and not train or participate in any team activities for a full two weeks.