Liverpool fans have urged the Premier League to address the offside protocols after Wolves goalkeeper Rui Patricio suffered a serious-looking injury.
The Portuguese shot-stopper collided with his own teammates, Conor Coady and required lengthy treatment on the field before being stretchered off the pitch.
The delay last over 10 minutes as Patricio was assisted by medics, with Liverpool winning the match 1-0 thanks to Diogo Jota 's first-half goal.
The incident occurred after Mohamed Salah was slipped through on goal and as he scored past the goalkeeper, Coady's leg appeared to hit Patricio in the head.
Salah was ruled offside by the linesman, which was the correct call, but plenty of Liverpool fans online suggested the injury should bring the current process around offside decisions back into focus.
After the final whistle, the official LFC account tweeted: "Three points but tonight our thoughts are with Rui Patricio".
And Jota sent a message to Patricio in his post-match interview, saying: "Life is more important. I hope it's nothing too serious and he has a quick recovery."
Speaking to the media tonight, Wolves boss Nuno Espírito Santo confirmed that Patricio "is okay" and could remember the incident.
Jurgen Klopp has previously complained about the offside protocol, warning a serious injury would occur.
Despite both teams making all three of their substitutions, both clubs were allowed to make an additional charge each as a result of the heavy stoppage.
A Premier League statement explains: "Following extensive consultation with medical experts and National Associations to find ways to improve management of possible neurological head injuries in football matches, the IFAB have approved trials to use APCS.
"The IFAB, who oversee the Laws of the Game, believe that where there is any doubt about a player having been concussed the players should be protected by being "permanently" removed from the match and to facilitate this, the player’s team should not suffer a numerical disadvantage by prioritising the player’s welfare.
"Premier League clubs agreed in principle on 17 December 2020 to take part in the IFAB trial, using two APCSs for each match."
The concussion substitution rules allow both clubs to make one additional change, with John Ruddy coming on for Patricio.
