Liverpool won the Champions League in 2019 and the following year took the club's first league title in 30 years.
This season, however, has started heavier and the team has four straight defeats in the Premier League.
It did not go better in the FA Cup tonight.
After a mistake by Rhys Williams, Manchester United were able to take the lead with 2-1 at the beginning of the second half.
Williams misjudged a long ball and failed to hit the ball to hit it.
Instead, the ball went to Marcus Rashford who gave the home team the lead.
However, the reply came ten minutes later.
United neglected in the play-off phase, which Liverpool took advantage of.
The guests quickly turned the game around and found Mohamed Salah who in the middle of the box put 2-2 with the wide side, his second goal of the match.
Nilsson Lindelöf played the entire match
But it did'nt help.
With twelve minutes left, the decision came.
On a free kick just outside the penalty area, Bruno Fernandes stepped forward and pulled it 3-2 in the goalkeeper's left corner.
The ball went over a Liverpool player, who pulled his head away, and into next to the post.
Fernandes was substituted in the 66th minute - just over ten minutes later, he sent United on in the FA Cup.
Victor Nilsson Lindelöf played the entire match for United.
The Swedish defender made a stable match apart from the situation at Liverpool's 1-0 goal.
Nilsson Lindelöf ended up in the wrong position when Roberto Firmino found Salah with a ball between the back line.