Haaland, who scored four league hat-tricks in a record-shattering first season with City, is already in the groove and his triple against Fulham took his season's goal tally to six.
Julian Alvarez and Nathan Ake were also on target for City in the first half with Tim Ream equalising for Fulham but Haaland then grabbed centre stage as the hosts cut loose.
City, bidding to win an unprecedented fourth successive English league title, have a maximum 12 points with Spurs on 10 after they demolished Burnley 5-2 at Turf Moor.
Third-placed West Ham United, who beat Luton Town 2-1 away on Friday, also have 10 points from their four games.
Chelsea's stuttering start to the season under Mauricio Pochettino continued as they lost 1-0 at home to Nottingham Forest for whom substitute Anthony Elanga was on target.
Everton scored their first goals of the season and gained their first point in a lively 2-2 draw at Sheffield United.
Brentford drew 2-2 at home to Bournemouth.
Brighton's 18-year-old Ferguson grabbed the headlines when his side welcomed Newcastle in the late game, netting an opportunist first goal and then a beautiful curled effort from distance before completing his hat-trick with a deflected shot.
The win moves the Seagulls to fourth spot on nine points.
Haaland exploits
Haaland's latest exploits earned him another record as he became the fastest to 50 goal involvements in the Premier League with 41 goals and nine assists. He reached the milestone in 39 games compared to the 43 it took Andy Cole.
"Important win, we go into the international break having won four in four. Good start to the season," Haaland said.
"I'm back. No problem for me. I am always hungry. It's a new season and I am ready for it."
With manager Pep Guardiola absent following back surgery City took a while to get going against Fulham.
Haaland set up the opener for Alvarez but Fulham levelled soon after through Ream who was left unmarked.
City went ahead in controversial fashion in first-half stoppage time when VAR allowed Ake's header to stand despite Manuel Akanji being in an offside position in front of the keeper and making an effort to get a touch on the ball.
Fulham boss Marco Silva was booked for his angry reaction.
Alvarez set up Haaland's first goal in the 58th minute and the Norwegian then buried a penalty after Issa Diop fouled Alvarez. Haaland completed his hat-trick with a first-time finish from a cut-back by Sergio Gomez.
Son hat-trick
Tottenham's strong start to the league campaign continued at Burnley with Son scoring his fourth Premier League hat-trick although they had to come from behind.
Lyle Foster slotted Burnley ahead after four minutes but Son opened his account for the season with a dinked finish after 16 before Cristian Romero put Spurs ahead with a powerful effort in first-half stoppage time.
James Maddison made it 3-1 before Son completed his hat-trick with two goals in quick succession to lift Ange Postecoglou's side into second place.
"Once we got to grips with it I think thought we were dominant in just about every area," Postecoglou said.
Chelsea have spent around $1 billion in transfer fees since the new ownership led by American Todd Boehly and Clearlake Capital completed their takeover of the club in May 2022.
But they remain very much a work in progress under Pochettino with only one win from their first four league games.
Forest's Elanga struck early in the second half and a toothless Chelsea could not respond. There were some boos at the final whistle.
"We're not playing fantastic but I think the performance is not bad. The fans want to win and we need to give the possibility for them to be happy," Pochettino said.
Everton took the lead at Sheffield United through Abdoulaye Doucoure but trailed at halftime as the home side's new signing Cameron Archer levelled and then forced an own goal when the ball rebounded off England goalkeeper Jordan Pickford's back.
Arnaut Danjuma made sure Everton went home with a draw.