Fulham boss Scott Parker says Aleksandar Mitrovic’s Covid-19 rule breach was “not acceptable”.
The Serbia striker was one of a number of high-profile players to have broken coronavirus restrictions over the festive period.
Mitrovic, 29, was pictured on New Year’s Eve with fellow Serb Luka Milivojevic, Crystal Palace’s captain.
Palace manager Roy Hodgson has made it clear to his players no further breaches will be accepted.
Parker, who himself had to self-isolate over Christmas, said he was “bitterly disappointed” after seeing the picture.
“He understands he’s made a mistake,” said Parker. “He understands it was irresponsible. It’s not acceptable. We’ve dealt with that as a football club internally.”
Hodgson issued a stern warning to his players saying that they would be punished if anyone would was found to have broken government guidelines again.
“The consequence would be harsher, there is no doubt about that,” he said.
“The players have had it made very clear to them in the future there is to be no breaking of any government guidelines.
“And anybody who does will face the consequences, and the consequences will be very strong ones and ones the players don’t want to suffer.”
Palace skipper Milivojevic, 29, issued an apology and made a donation to the NHS after he conceded he “let the fans, the club, my manager and team-mates down”.
Meanwhile, Fulham midfielder Kevin McDonald, 32, expressed his frustration after Aston Villa announced that they were closing their training ground because of a “significant” coronavirus outbreak at the club.
“How many more outbreaks and training-ground closures until football needs to stop?” he said on Instagram.
“Shambolic, literally treated like guinea pigs.”
Fulham’s past two matches, away at Tottenham and Burnley, were postponed because of coronavirus cases at the west London club.
- Stream eight live FA Cup third-round games this weekend on BBC iPlayer, the BBC Sport website and app. Find out more here.