Luis Diaz put the home side ahead with less than five minutes on the clock and they never looked back, with Ralf Rangnick’s side struggling before the break to get a touch, let alone fashion a chance.
Mohamed Salah went into the match without a goal from open-play since February but he brought an end to that run as Liverpool took complete control. Sadio Mane got himself on the scoresheet after the break to put the result beyond any doubt, before Salah got his second of the night late on.
The win moves them two points clear of Manchester City, though Pep Guardiola’s side are in action on Wednesday night at home to Brighton. Liverpool’s attention now turns to another of their big rivals, with Everton making the short trip across Stanley Park on Sunday.
United were without Cristiano Ronaldo as expected, after the tragic death of his baby son. Both sets of fans joined together in applause as a show of support to him and his family in the seventh minute at Anfield.
By that point, Liverpool had already taken the lead. Mane had time to set Salah away and the Egyptian had the freedom of the right wing to look up and square it for Diaz, who had the simplest of finishes from close range.
Paul Pogba was then forced off with injury inside ten minutes as the visitors made the worst possible start to what was an astonishingly one-sided 45 minutes. United were rattled, Liverpool imperious, and midway through the opening half their lead was doubled.
It was a sensational move too. Joel Matip played a one-two with Diaz before finding Mane, who sent a sublime first-time pass to Salah. He finished emphatically, showing no signs of a man who had been without a goal.
Thiago does not need the freedom of midfield to run a match, but United generously gave it to him just in case. Diaz had the ball in the net again, though this time the linesman’s flag denied him. The half-time whistle was a welcome one for the away side.
Jadon Sancho was introduced at the break and he helped United to produce a slightly improved display. A bright counter from the visitors saw him cut inside and have a tame effort comfortably saved by Alisson.
The winger then beat a couple of challenges and slid a pass through to Marcus Rashford, who was denied by the goalkeeper and Alisson was quickly up to save from Anthony Elanga too. The offside flag then went up, but replays showed the goal would have counted.
Just as United were starting to threaten something resembling a comeback, Liverpool clicked into gear again. Andy Robertson charged out of defence to intercept a pass and the hosts were away on the counter. He played it wide to Diaz, who cut it back for Mane to perfectly finish into the far corner.
That brought an end to the competitive element of the match as the home side cruised through the final stages. There was still time for Salah to come in off the right and loop an effort over De Gea with the help of a slight deflection off Aaron Wan-Bissaka, taking the aggregate score between the two sides this season to 9-0.
A quadruple has long been seen as almost impossible for a side to achieve, but with every passing win and dominant display from Liverpool it becomes ever-more conceivable.