Liverpool's Salah, the top scorer in the Premier League, broke the long silence and scored two goals, widening the gap with second-placed scorer Son Heung-min to five goals.
Salah put on a one-man show against Manchester United without Ronaldo.
In the 5th minute of the first half, he helped Dias open the scoring with a sharp cross, and finally broke the goal silence in the 22nd minute.
He closed the back space with his fantastic breathing with Mane and finished with his left foot, restarting the scoring store after 7 games and 39 days.
Salah scored the league's 22nd goal with a sharp penetration even at the end of the game, beating 2nd place Heung-min Son by 5 goals.
With a 4-0 win, Liverpool beat Manchester City, which had played one game less, to regain the lead in six months.