Haaland scored twice in a 4-1 win over West Ham as City secured back-to-back victories in the Premier League for the first time since late October.
It came on the day Chelsea's winless run extended to four matches after drawing at Crystal Palace 1-1 and as Ange Postecoglou was left fuming following Spurs' 2-1 home defeat by Newcastle.
Anthony Gordon scores for Newcastle in a win at Spurs that puts more pressure on Ange Postecoglou. (AP PHOTO)
City had played nine league games and won just once, dropping them out of the Champions League qualification spots, but there were better signs against West Ham, not least with Haaland looking sharp in front of goal.
The Norway striker headed in Savinho's cross to make it 2-0 in the 42nd minute and chipped the goalkeeper for 3-0 in the 55th after running onto another pass from Savinho.
Either side, there was an own-goal and a strike from Phil Foden before Niclas Fullkrug pulled one back for West Ham.
Cole Palmer had put Chelsea ahead against Palace but Jean-Philippe Mateta equalised in the 82nd minute.
Chelsea have drawn twice and lost twice since December 22, damaging a title bid that had been picking up some steam — even if manager Enzo Maresca never accepted his team were realistic challengers.
Chelsea's Cole Palmer looks fed up after they dropped points in the draw at Crystal Palace. (AP PHOTO)
Fourth-placed Chelsea are nine points behind leaders Liverpool, who have two games in hand, the first being at home to Manchester United on Sunday.
At Spurs, Isak grabbed the 38th-minute winner, his 13th goal of the season, and ninth in his past seven games, but Postecoglou, who'd watched Dominic Solanke put his side ahead after four minutes, was left raging about Anthony Gordon's equaliser soon after which he felt should have been ruled out for an earlier handball.
Thomas Tuchel was in the stands in his first scouting mission in his role as the recently hired England coach.
It was a fifth straight win for fifth-placed Newcastle, while Tottenham stayed in the bottom half of the standings with just one point from their last four games.
A change in manager hasn't helped Southampton.
The league's last-placed team were beaten by Brentford 5-0 at home for a third straight defeat under Ivan Juric, who was hired in December to replace the fired Russell Martin. Southampton have just one point from four games under Juric.
Bryan Mbeumo scored two of Brentford's goals and has 13 for the season in the league.
Aston Villa are eighth having secured a 2-1 home win over second-bottom Leicester thanks to Leon Bailey's 76th-minute strike, with Ross Barkley having earlier put them in front before Stephy Mavididi replied.
Seventh-placed Bournemouth, unbeaten in eight, were 1-0 winners against Everton at the Vitality Stadium courtesy of David Brooks' 77th minute goal.
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