The Senegalese international won the penalty for the Reds after 13 minutes that their star forward smashed into the back of the net.
Jurgen Klopp’s side have a lot riding on the game as the blue side of Manchester provide their biggest test for consecutive titles.
They could not hold onto the lead for half time, though, as Gabriel Jesus struck on the half-hour to equalise.
And footage has emerged of the tension appearing to get to Liverpool’s star forwards moments after gaining the lead.
In the clip, Salah shares high-fives with his team-mates after smashing past Ederson at the Etihad Stadium.
When Mane approaches him, though, the Egyptian’s face immediately drops and he starts shouting.
The No.11 wags his finger at the Senegalese forward, appearing to try and stop him from talking and putting his hands up.
Liverpool’s forwards continue their conversation even as Salah receives congratulations from Joe Gomez and Trent Alexander-Arnold.
This footage was shared on Twitter, where the Anfield faithful were left worrying about their top-scoring players.
“Mane and Salah arguing,” one supporter said.
“What was that Mane-Salah argument about?”
While a third speculated what the pair were talking about, with: “Salah telling Mane ‘don’t talk to me’ straight after he scored the penalty.
“You think Mane was telling him where to shoot the penalty!!’”
And a fourth added: “Salah and Mane hate each other, don’t they really?”
With a fifth simply writing: “Salah and Mane are a problem.”
The Reds’ No.11 started the game ahead of Mane, who is in a trio with Roberto Firmino and Diogo Jota.