Haaland opened the scoring from the penalty spot after Rasmus Hojlund grabbed a hold of Rodri in the box, and it was only goalkeeper Andre Onana who prevented City taking a bigger lead into the break.
Haaland had a chance to complete his hat-trick, but chose to set up Phil Foden to add City’s third. There were boos at full-time after United’s latest poor display, while Bruno Fernandes and Antony were booked for petulant tackles near the end.
Here are how the players rated at Old Trafford.
Andre Onana, 7
Carried on the momentum from Tuesday’s penalty stop with a couple of impressive saves - both from Haaland. There was nothing he could do about the penalty or Haaland’s second close-range header, but he did spill Rodri’s effort for Foden’s third.
Diogo Dalot, 3
Completely overwhelmed by City’s dangerous left side - Grealish and Bernardo Silva created several two-on-ones and Dalot didn’t stand a chance with United’s set-up looking so exposed.
Harry Maguire, 5
Maguire was solid enough and tried his best to keep the United ship afloat, but United struggled to move the ball forward and the centre-back did too. By no means is Maguire the biggest problem in the United side right now.
Jonny Evans, 4
It’s not being unfair to Evans to say that the centre-back should not be starting a Manchester derby in the year 2023. He made no serious errors but Haaland comfortably won the match-up.
Victor Lindelof, 3
Very obviously not a left back. A strange decision from Ten Hag, and Lindelof was replaced by Sergio Reguilon late on without making an impact.
Sofyan Amrabat, 4
Hooked off at half time after United failed to compete in midfield with City - but it actually made Ten Hag’s side worse.
Scott McTominay, 5
United’s biggest threat, which on days like today is a damning indictment for the club. Forced Ederson into a strong save and offered runs forward, but United need so much more.
Bruno Fernandes, 3
An anonymous performance in an attacking sense and offered nothing in terms of leadership until he decided to try and take a City player down with him with some late challenges. Too often goes missing when United get thrashed.
Christian Eriksen, 3
Struggled to keep up with City’s movement in midfield, Bernardo, Grealish and Foden rang rings around him.
Marcus Rashford, 4
Last season’s Rashford might have scored when United had some early bright moments on the break - but Rashford looks so low on confidence playing for United right now. A dragged finish wide of the target when United were 2-0 down was illustrative of that.
Rasmus Hojlund, 5
His first Manchester derby will be remembered for his foul on Rodri in the box. It might have been harsh, but Hojlund was naive. After that, his touch let him down when Foden’s back-pass offered the chance for an equaliser. Taken off by Ten Hag with United behind, to boos from Old Trafford at the manager’s decision.
Mason Mount, 4 - Brought on at half time but looks a shadow of his former self and it gave City even more space to exploit.
Produced a strong arm to deny McTominay’s fierce strike before half time, in a classic example of the goalkeeper needing to be sharp despite the action all taking place in the other half.
Kyle Walker, 8
Set up an early chance for Foden with his run to the byline and header back across goal. Rashford was limited to only a few openings on the left and Walker comfortably won the duel with his England teammate. Switched off on one occasion, but Rashford couldn’t punish him as he dragged wide.
Ruben Dias, 8
The centre-back was barely tested but looked assured whenever called upon. Hojlund had a couple of breaks but City’s recovery speed was always strong.
Josko Gvardiol, 8
Slotted in nicely on the left side of City’s defence - adding to Bernardo and Grealish’s complete domination on that area of the pitch. Carries the ball forward well.
John Stones, 8
Another in blue who cruised through the derby after a tricky opening 10 minutes. Stones made an excellent recovery run to pressure Hojlund following Foden’s loose back-pass.
His fall may have convinced referee Paul Tierney to point to the penalty spot after Hojlund wrapped an arm, but Rodri otherwise controlled the midfield well - showing United what they were missing without Casemiro.
Phil Foden, 8
Foden offered plenty of quality touches throughout and was one of the standout performers in the City side, alongside Bernardo and Grealish. Played a peach of a volleyed pass through to Haaland but was then lucky his back-pass wasn’t punished by Hojlund.
Julian Alvarez, 8
A but quieter than the three other City forwards behind Haaland but his touch and timing of pass was still beyond what United could deal with. The World Cup winner added to the dominance with his intricate style.
Bernardo Silva, 9
The Portuguese was a class above and helped City take complete control with his clever touches and passes on the left. Routinely found gaps in United’s defence and was a menace throughout with his crossing - while still showing excellent defensive instincts.
Jack Grealish, 8
More than justified his inclusion over Jeremy Doku. “We need Jack,” Guardiola said before kick-off and Grealish showed why with his control and touch. His link-up with Bernardo won City the match and Grealish also showed plenty of his own threat.
Erling Haaland, 9
What can you say? Enjoyed his first Old Trafford goal after keeping his head from the penalty spot and then didn’t let a poor miss get him down after Onana’s save. The same chance followed, and Haaland made no mistake. Could have scored a hat-trick but instead set up Foden. Eleven goals already this season.