With 76 points, the Reds are two steps ahead of Manchester City, which hosts Brighton on Wednesday evening (9:00 p.m.).
Relaunched in the race for the Champions League with their victory once morest Norwich (3-2) last weekend, the Red Devils remain three points behind Tottenham, 4th and last virtual qualifier for the Champions League.
But Manchester has one game more than Spurs and two more than Arsenal, 5th and ahead of them on goal difference.
A bit like in the semi-final of the FA Cup last Saturday once morest City (3-2), Liverpool took advantage of a completely missed first act from their opponent to take off.
It must be said that without Raphaël Varane, injured, without Cristiano Ronaldo, bereaved by the loss of one of his newborn twins and who received a beautiful tribute from Anfield supporters in the 7th minute, like the number of his jersey , United presented themselves seriously weakened.
The loss, to an apparent muscular injury, of Paul Pogba following less than 10 minutes did not help, even if the Reds were already in front so early in the game.
Faced with the 3-4-3 set up by Ralf Rangnick at kick-off, Liverpool wandered off.
With a brace and an assist for Mohamed Salah, a goal and an assist each for Luis Diaz and Sadio Mané, the attacking trio of the Reds was untenable, ahead of a Thiago Alcantara who splashed the game with his class in the middle.
It only took 5 minutes for the Colombian, following a magnificent counter and an ideal service from Salah, to open the scoring (1-0, 5th).
Sometimes considered less decisive since the lost final in the African Cup of Nations, Salah responded to skeptics by scoring the second goal, following a blind opener from Sadio Mané (2-0, 22nd).
Returning to the locker room, United had not taken a shot on goal and seemed completely overwhelmed, with the memory of the 5-0 conceded in the first leg at Old Trafford haunting him.
Back to four behind and a little more present in attack, the Red Devils might not do anything in the second half either.
Mané, with a recovery while loosening the left, drove the point home (3-0, 68th), then imitated by Salah with a clever and slightly deviated ladle (4-0, 85th).
Winner of the League Cup, qualified for the FA Cup final once morest Chelsea and for the semi-finals of the Champions League and neck and neck with City in the league, the dreams of an unprecedented quadruple on the banks of the Mersey are more alive than ever.