The Magpies midfielder has told his boss in no uncertain terms that his tactics are not quite up to scratch...
Barton was sent off in the 77th minute of the game for a two-footed lunge on Reds midfielder Xabi Alonso.
Shearer struggled to disguise his disappointment with the 26-year-old when speaking to the press after the match.
It has since been alleged that the pair exchanged harsh words in the dressing room immediately after the defeat at Anfield.
"You’re a s*** manager with s*** tactics," Barton is said to have told Shearer in response to being criticised for his reckless challenge.
Apparently, the pair had to be pulled apart as tempers flared.
"It was unbelievable. They were like two stags," a Newcastle United inside source is quoted as saying.
"Shearer told Barton he had made a mistake putting him back in the team, that he thought Barton was good enough to do it but he had shown he wasn’t.
"Joey shouted at Alan that he was the best player at the club, which was why he had to play him.
"Alan said he wasn’t, called him s*** and Joey replied that he was a s*** manager with s*** tactics.
"At that point, it looked like they were going to have a full-scale brawl and had to be dragged apart.
"Shearer was really angry, not just because of the stupid red card but because it means Barton will be missing for the last three Premier League games when Newcastle need everyone available.
"Alan gave Joey the big build-up during the week, saying what an important player he could be in Newcastle’s fight against relegation, and then he does that.
"You wonder what goes on in Joey’s head."
Barton, a £5.8 million signing from Manchester City in 2007, who is thought to be earning between £50,000-60,000-a-week, has made just 32 appearances for the Toon since arriving at St. James' Park.
The one-time capped England international will miss Newcastle's remaining three Premier League fixtures, which may prove to be costly to a club who are three points adrift of safety in the relegation zone.
Ricky Brooks, Goal.com