Not only does the result move them 19 points clear of Jose Mourinho's Man Utd, it also means they return to the top of the Premier League ahead of Manchester City.
There were impressive performers all over the pitch for Liverpool, from Nathaniel Clyne making his first appearance of the season to Xherdan Shaqiri coming off the bench to score twice.
However, Fabinho really caught the eye too and his dominant display was all the more encouraging when you consider the amount of time it's taken him to adapt to English football.
As you'd expect, Liverpool supporters were full of praise for their summer signing after the victory, but how did the opposition's fan base react to his performance?
Fabinho improving after slow start at Liverpool
Fabinho joined Liverpool from 2016-17 Ligue 1 champions Monaco over the summer for an initial fee of £39 million.
He initially struggled to get into Jurgen Klopp's starting XI and actually didn't make his league debut until October 20, as a 69th-minute replacement for Adam Lallana at Huddersfield.
Against so-called lesser opposition, the Brazilian has shown signs of his unquestionable quality but he silenced all the doubters during Liverpool 3-1 Man Utd.
Fabinho shines on big stage in Liverpool 3-1 Man Utd
It was a massive occasion, with Klopp looking for his very first league win over United, but Fabinho wasn't overawed - in fact, he shined.
Throughout the match, the defensive midfielder was aggressive, physically strong, energetic when he pressed Man Utd's players and extremely assured in possession.
United were often slow to close him down, but rather than dawdle when he had time on the ball, he produced key moments of quality such as his assist for Sadio Mane's opener.
Fabinho's positional awareness was the reason Clyne and Andy Robertson felt so confident bombing forward at the same time, and overall, he put in a top-class showing.
What Man United fans are saying about Fabinho
Man Utd fans were understandably disappointed after their team's lacklustre display at Anfield, yet even they couldn't help but praise the 25-year-old on Twitter.
Red Devils supporters feel the ex-Monaco man, who can also play at right-back, proved how much more technical quality he possesses compared to Nemanja Matic.
In fact, United fans are regretting paying Chelsea £40 million for the two-time Premier League winner and admitting they'd have rather spent that money on signing Fabinho.
Check out the best tweets below:
The Serbian midfield anchor has pretty much been an ever-present in Mourinho's side since moving to Old Trafford in 2017 and, this term, all that football has caught up to him.
Matic has looked slow and indecisive on the ball in several different matches this campaign; a stark contrast to the classy and dynamic display Fabinho produced on Sunday.
While Man Utd sit 11 points outside the top four, Liverpool and Fabinho will hope to stretch their lead at the top in upcoming clashes with Wolves and Newcastle United.
Football fans: Do YOU think Fabinho is better than Matic after watching Liverpool 3-1 Man Utd? Have YOUR say in the comments box below!News Now - Sport News