MO Salah's bust-up with Jurgen Klopp exploded over a touchline handshake snub.
Liverpool boss Klopp expected a handshake with Salah before he went on as sub in the 2-2 draw at West Ham and, although they eventually did a fist bump, the damage was done.
A source said: "This has happened occasionally with Jurgen and other players.
"He is very big on interaction with his subs before they go on and felt it didn't happen at first with Mo.
"Mo was obviously annoyed at being left out of the team and wasn't in the best of moods while Jurgen wasn't happy with his behaviour."
Salah snubbed Klopp at the end of the match too as he came off the pitch, shaking hands with Hammers boss David Moyes but ignoring his own manager.
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The source added: "The players were given a couple of days off after the match and are meeting up again on Tuesday.
"It is hoped that by then tensions will have calmed down."
Klopp attempted to play down talk of a rift with his star man after the match, despite warmly embracing Darwin Nunez and Joe Gomez as they stood alongside Salah waiting to come on.
The Reds boss said: “We spoke about it in the dressing room, but it’s done for me. That’s it.”
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Salah strops
FIVE times things have got heated during Mo Salah's Liverpool career
West Ham 2 Liverpool 2 - April 28, 2024
Salah gets into a heated argument with Klopp as he refuses to shake the manager's hand before coming on at the London Stadium.
Liverpool 3 Sheffield United 1 - April 4, 2024
Salah shakes his head as he is subbed off during Liverpool's 3-1 win over the basement club.
Chelsea 1 Liverpool 1 - August 13, 2023
Salah storms off the pitch after being replaced on 77 minutes on the first day of the season.
Brighton 1 Liverpool 1 - November 28, 2020
Salah throws his arms up in the air and barely looks at Klopp after being subbed off. Brighton go on to equalise with a last minute penalty.
Burnley 0 Liverpool 3 - August 31, 2019
Salah gets in a public spat with Sadio Mane after failing to pass to the winger. Team-mate Roberto Firmino says the row had been brewing for some time.
However Salah was still feeling hot after the final whistle and held his tongue for fear of getting in trouble.
The Egyptian said: “There's going to be fire today if I speak.”