The FA could launch disciplinary action against Liverpool forward Ryan Babel after he tweeted a photo of referee Howard Webb in a Manchester United shirt.
Press Pass Extra: Babel's cheeky tweet
The mocked-up picture appeared on the winger's official Twitter page a matter of hours after his side exited the FA Cup at the hands of United at Old Trafford.
Webb, who refereed the game which the home side won 1-0, angered Liverpool by awarding a first minute penalty against them and then sending off captain Steven Gerrard.
The FA confirmed: "We will definitely look into this matter."
As well as the photo, Babel wrote: "And they call him one of the best referees? That's a joke. SMH."
SMH is an abbreviation for "shaking my head" and Babel is not the first Liverpool player to run into trouble on Twitter this weekend. Babel has now apologised, adding to his page while also commenting on watching the evening's Spanish football. "My apology if they take my posted pic seriously. This is just an emotional reaction after losing an important game," he said. "Sorry Howard Webb."
On Saturday, defender Glen Johnson, who missed Sunday's game as his wife had gone into labour, launched an attack on TV pundit Paul Merson after he criticised his performances for the Reds.
"Comments from alcoholic drug abusers are not really gonna upset me and who is Paul Merson to judge players, he was average at the best of times," Johnson wrote.
"The only reason he's on that show is coz he gambled all his money away. The clown!"
New Liverpool manager Kenny Dalglish called Webb's penalty decision a "joke" and also disputed Gerrard's dismissal, but his son Paul, the former Newcastle striker, went even further via his own Twitter account.
He said: "Fergie has his puppet Howard Webb on a piece of string." He also made fun of Webb being given an MBE at the start of the year, adding: "Howard Webb MBE. Manc of the Busby Empire."
Meanwhile, Greater Manchester Police have confirmed that 15 arrests were made, believed to be largely Liverpool fans in relation to the smashing up of toilets in the away section of Old Trafford, and the damaging of seats.