West Ham 1 - 3 Man City
Manchester City served notice of their title ambitions by outclassing West Ham to move level on points with Arsenal at the top of the Premier League.
City took a deserved lead when the superb Yaya Toure fired past Robert Green from Gareth Barry's cut-back.
And they made it two at a subdued Upton Park as Yaya Toure's shot hit a post and went in off Green's back.
Adam Johnson rounded Green to seal the points before James Tomkins headed a consolation for rock-bottom West Ham.
The result sees big-spending City leapfrog Chelsea and Manchester United to join Arsenal on 32 points, although the Gunners' goal difference is superior by five.
Chelsea will go top if they win at Tottenham on Sunday, while Arsenal and United have the chance to take pole position when they meet at Old Trafford on Monday.
West Ham, by contrast, stay bottom of the league on 12 points with only two wins all season.
Their loss at Sunderland last Sunday kept them at the foot of the table, but a run of five home games without defeat in all competitions provided cause for optimism ahead of this one.
And despite featuring four changes from the side beaten on Wearside, the Hammers looked lively and cohesive from the outset - snapping into tackles and breaking forward at pace.
Boss Avram Grant dropped Carlton Cole to the bench as Frederic Piquionne came in to partner Victor Obinna up front, and the Frenchman was ably supported by wingers Pablo Barrera and Junior Stanislas.
Yet it was City, unbeaten in the league since October and with five victories from nine away games, who carved out the best chance in the early stages.
With captain Carlos Tevez ruled out of a return to his old club through suspension, City fans could have been forgiven for approaching the match with trepidation.
The Argentine striker had scored 48% of his side's league goals this season - a higher proportion than at any other club.
But it was his replacement, the Brazilian forward Jo, who produced a fine run and low cross from the left to tee up Mario Balotelli in the fourth minute.
The in-form Italian ghosted in front of Matthew Upson at the near post, only to angle his first-time finish wide of the far upright.
Seemingly unfazed by that close shave, West Ham went back on the front foot and Scott Parker volleyed wide before Stanislas curled a free-kick over and shot powerfully at Joe Hart after cutting in from the left.
However, City gradually began to exert an influence on proceedings - dominating possession and frustrating their opponents with a slick brand of pass-and-move football - and reward was forthcoming.
West Ham were warned of the threat post by Yaya Toure when he ran half the length of the pitch before shooting straight at Green - but the lesson was not heeded.
In the 30th minute, the Ivorian fed Gareth Barry on the left, got ahead of a dozing Jonathan Spector to meet the cut-back and rifle a first-time drive past Green from the edge of the penalty area.
It was a stunning finish and one which West Ham worked hard to bounce back from, Parker dragging a drive narrowly wide and Piquionne glancing a header over from Julien Faubert's cross.
City reached half-time fairly comfortably and the flat atmosphere at Upton Park did not exactly make for a rousing opening to the second period.
Obinna drilled in a promising centre from the left that was gathered by Hart with Piquionne lurking, but a second City goal was looking more likely than a West Ham equaliser.
Yaya Toure stung Green's palms with a fierce strike following another ranging run, while Balotelli was squeezed out by Tomkins after being released by the former Barcelona man.
Balotelli was becoming increasingly irritated by his inability to make an impact and shortly after picking up a caution for dissent, he was withdrawn by manager Roberto Mancini.
The 20-year-old's petulance appeared to disrupt his team's rhythm and allowed the momentum to swing back into West Ham's hands.
Grant's men set about pressing with real intent, forcing a couple of defensive mix-ups and an unsuccessful penalty appeal for what looked like a handball by Yaya Toure.
On came Kieron Dyer and Cole as Grant went for all-out attack and there was to be another goal - but it went the way of City.
Yaya Toure raced forward to collect Nigel de Jong's pass and waltzed past Tomkins to go one-on-one with Green. His shot came back off the woodwork but ricocheted in off the goalkeeper's back.
It was three when Johnson, on for Balotelli, latched on to David Silva's slide-rule pass and evaded Green to roll into an unguarded net.
Tomkins nodded Obinna's corner past Hart with the aid of a deflection off Kolo Toure at the death, but it proved too little too late.