Newcastle have confirmed Lee Bowyer and Kieron Dyer will both stay at the club despite fighting each other during the 3-0 defeat to Aston Villa on Saturday.
But Bowyer has been fined the maximum six weeks' wages by the Magpies, thought to be around £200,000.
The pair were sent off for brawling but shook hands after training on Monday and boss Graeme Souness revealed they have contested Dyer's dismissal.
Souness said: "They've spoken over the weekend and have had a laugh about it."
He added on the club's official website: "They appreciate the seriousness of the incident, but they were laughing because they get on very well together.
"There has been an implication they have been at loggerheads for a long time, but this is completely without foundation."
A Newcastle statement read: "Lee Bowyer has been handed an unprecedented fine, severely censured and additionally warned as to his future conduct.
"The decision to fine and censure Bowyer was taken after chairman Freddy Shepherd and Graeme Souness interviewed both players at the club's training ground on Monday.
"The fine, amounting to six weeks wages, is the highest fine handed out by the club."
Dyer and Bowyer already both face a three-match ban for violent conduct but could also be charged with bringing the game into disrepute.
The Football Association will study referee Barry Knight's report before making a decision over any possible charges on Tuesday.
Northumbria Police meanwhile, have confirmed that they will investigate the brawl.
"A senior officer from Newcastle area command has been assigned to investigate the circumstances of this incident," said a statement.
"That officer's report will consider whether or not further police action is required and whether any offences have been committed.
"The football club is co-operating fully with our inquiries, which are expected to take some time.
"While initially we have not received any complaints arising from this incident we have now had concerns expressed by members of the public and those will form part of inquiries."
Shepherd admitted Saturday was his worst day as Newcastle chairman.
"I could hardly believe what my eyes were telling me. I am deeply embarrassed, hurt and angry about what happened. It was just unbelievable," said Shepherd.
"It was a black day for Newcastle United and I never thought I would see two of our own players fighting."
Captain Alan Shearer, who announced he was delaying his retirement for another year on Friday, launched a scathing attack on the two players for letting the club down.
"Once again the good name of Newcastle United is being dragged through the dirt," Shearer told The Sun.
"What happened was a disgrace, there is no defence for it and I made my feelings known in the dressing room.
"I'm very angry still and very frustrated by it all, especially when things had been going so well and the spirit within the camp has been so good over the last few month.
"Our dirty linen has been hung out for the country to witness yet again."
Fighting on the pitch is not without precedent - ex-Newcastle midfielder David Batty traded punches with Graeme Le Saux when both were playing for Blackburn in a Champions League tie against Spartak Moscow in 1995.
Uefa suspended and fined both players after the incident.
John Hartson received a £20,000 fine from West Ham in 1999 after an ugly incident on the training ground which led to him kicking Eyal Berkovic in the face.
And Arsenal midfielder Patrick Vieira reportedly scuffled with team-mate Lauren on the team coach following this season's Champions League draw with Rosenborg.