City took the lead after 22 minutes against Brighton when Haaland claimed his 21st goal of the season. The powerful Norwegian barged Adam Webster out of the way as he raced onto a long ball from Ederson and coolly rolled the ball into an unguarded net.
City doubled their lead just before half-time with yet another goal from Haaland, this time from the penalty spot. Referee Craig Pawson allowed play to go on after Bernardo Silva went down in the area under a challenge from Lewis Dunk.
The decision was reviewed in the next stoppage in play and consequently, and controversially, overturned. Haaland did not waste the opportunity as he smashed home from 12 yards to put him in sight of a fourth hat-trick of the season.
Brighton pulled one back early in the second half through Leandro Trossard. Moments after Riyad Mahrez had gone close to a City third at the other end, the visitors broke and Trossard lashed a fine shot inside the near post from the edge of the area.
Kevin De Bruyne eased any nerves for City by making it 3-1 with a superb strike 15 minutes from time. The Belgian picked his spot from 25 yards out and curled an effort into the top corner.
Sussex World reporter Logan MacLeod was at the Etihad Stadium and his player ratings gallery is below...
1. Robert Sanchez - 6-10
Will be having nightmares about Haaland tonight. Caught in no man's land for the City striker's first goal. Had the unenvious job of facing Haaland from the penalty spot no chance of stopping him from 12 yards. Made a vital save to deny Mahrez in a 1 v 1. Nothing he could have done to stop De Bruyne's 25-yard belter. 6/10 Photo: Justin Setterfield
2. Joel Veltman - 6/10
Came off injured in the 65 minute. Defended well and made no real errors. Most noticeable action was flooring Jack Grealish. 6/10 Photo: Justin Setterfield
3. Lewis Dunk - 6-10
Tough day for the captain. Tasked with stopping the unstoppable Haaland. Got played by Haaland for City's first goal then gave away a penalty after VAR deemed he brought down Bernardo Silva. Much improved in the second half as Haaland went relatively quiet. 6/10 Photo: Julian Finney
4. Adam Webster - 6-10
Added to the list of defenders bullied by Haaland. Was brushed aside like a rag doll by for the City striker's first goal. Despite a poor first half he was much improved in the second providing good progressive passes, vital blocks in the box and defending on the front foot. 6/10 Photo: OLI SCARFF