(CNN) -- A Carlos Tevez goal in the second half gave Manchester City a 1-0 home win over defending English Premier League champions Chelsea at Eastlands on Saturday.
The defeat ended Chelsea's perfect start to the season and boosted City's own hopes just one day after their manager Roberto Mancini wrote off his side's title chances this season.
In a tight game of few chances, Tevez's goal came just before the hour mark from a City counter-attack.
Yaya Toure found Tevez on the halfway line and the Argentine burst forward before beating Petr Cech with a fierce shot from the edge of the penalty area which flew in off the post.
The excellent Toure came close to increasing the lead soon afterwards before Chelsea created some pressure and substitute Daniel Sturridge nearly scored a late equalizer against his old side.
But City defended superbly to restrict Chelsea's attacking efforts and held on for a deserved victory.
"We knew that we had to win today," Dutch midfielder Nigel De Jong told Sky Sports.
"If you saw how we defended from the front to the back that's why we kept a clean sheet."
Chelsea, who had gone into the game with five straight wins and a glut of goals, had their best moment in the first half as Florent Malouda's cross was headed back across goal by Alex and Branislav Ivanovic saw his own header come back off the bar.
Ivanovic headed back the rebound but England goalkeeper Joe Hart made a fine save.
Chelsea manager Carlo Ancelotti admitted his men had been below-par and that City's tactics had been a factor.
"We didn't play how we wanted. We suffered from the pressure that City put on us in midfield," the Italian told Sky Sports.
The shocks did not end with Chelsea's defeat as second-placed Arsenal were beaten 3-2 at home by promoted West Bromwich Albion.
Roberto Di Matteo's men led 3-0 at the Emirates and even saw Chris Brunt's penalty saved by Manuel Almunia as they dominated the home side.
Peter Odemwingie, Chris Brunt and ex-Gunner Jerome Thomas scored before a late Samir Nasri double gave Arsenal belated hope.
Arsenal's north London neighbors Tottenham Hotspur also stuttered to defeat at West Ham, the 1-0 win taking them off the bottom at the expense of Everton, who drew 0-0 at Fulham.
Frederic Piquionne headed West Ham's winner in the first half.
Liverpool looked to be heading for home defeat against Sunderland until captain Steven Gerrard scored a typical late equalizer in a 2-2 draw.
Manchester United can cut the gap on Chelsea to just one point with victory at Bolton on Sunday.