Two Mikael Silvestre headers ensured Rio Ferdinand's return to Manchester United's first team ended in triumph.
After Cristiano Ronaldo hit the post early on, Silvestre gave United the lead, ghosting in at the far post to head home Ryan Giggs' free kick.
Liverpool drew level soon after the break when Steve Finnan's header was inadvertently turned in by John O'Shea.
But Silvestre's aerial ability secured the points for United as the Frenchman powered a header past Jerzy Dudek.
This was by far United's best performance of the season, Ferguson's side attacking with verve and defending more solidly.
Liverpool were so lacklustre in the opening period that Ferdinand had the easiest of passages on his return to football after the end of his eight-month ban.
As well as playing Ferdinand, Ferguson also dropped goalkeeper Tim Howard, replacing him with Roy Carroll.
Liverpool missed a good opportunity in the opening minutes after Silvestre slipped trying to cut out Josemi's cross from the fight.
The cross reached Djibril Cisse, but the Liverpool striker embarrassingly missed his kick.
United responded through a twisting Ronaldo run and after shaking off Xabi Alonso the Portuguese winger hit the ball with the outside of right boot, his swerving shot rebounding off the post.
Soon after Ruud van Nistelrooy muscled his way past Sami Hyypia and struck a low shot that Dudek cleared with his feet.
On 20 minutes United took a deserved lead.
Ryan Giggs, making his 600th appearance for United, floated a free-kick across from the right and the unmarked Silvestre headed in at the far post.
United continued to create a steady stream of chances, Ronaldo volleying just wide and Gabriel Heinze drawing a good save from Dudek.
And van Nistelrooy headed a O'Shea flick-on agonisingly wide.
Ferdinand had a composed game
Just before half-time Liverpool suffered another blow when Dietmar Hamann had to come on for Steven Gerrard, who limped off through injury.
After the interval Liverpool came out with greater resolve and on 54 minutes Benitez's side drew level as United conceded a soft goal.
Finnan managed to reach an Alonso free-kick and his header rebounded off O'Shea, with the ball trickling over the line.
Midway through the second-half United regained the lead as Silvestre popped up in the box to send a header past Dudek from a Giggs corner.
An audacious Alonso shot from just inside the United half almost brought the equaliser for Liverpool but Carroll managed to recover his position just in time.
Man Utd: Carroll, Brown, Ferdinand, Silvestre, Heinze, Ronaldo, O'Shea, Keane, Giggs, Scholes, van Nistelrooy. Subs: Phil Neville, Smith, Kleberson, Fletcher, Ricardo.
Liverpool: Dudek, Josemi, Carragher, Hyypia, Riise, Finnan, Gerrard, Alonso, Kewell, Luis Garcia, Cisse. Subs: Baros, Diao, Hamann, Traore, Kirkland.
Referee: G Poll (Hertfordshire).