Man City earned a memorable victory at Stamford Bridge, where the drama started before kick-off with a first meeting between former Chelsea team mates John Terry and Wayne Bridge since news broke of Terry's alleged affair with Bridge's former girlfriend.
Bridge declined to shake Terry's hand as the teams took to the pitch, and the City defender emerged the happier man as Chelsea finished with nine men and lost their 37-match unbeaten home record.
After a forgettable opening 42 minutes the game came to life as Frank Lampard scored his 11th League goal of the season to put Chelsea ahead.
WELCOME RETURN
But City were soon on level terms, after Carlos Tevez pounced on a long punt up field from Bridge before advancing into the box and poking what looked a tame shot past stand-in goalkeeper Hilario.
It was a welcome return to Premier League action for Tevez, who was back for City after returning from compassionate leave in Argentina following the premature birth of his second daughter last week.
The Eastlands side had failed to win any of the four matches the Argentina forward had missed.
Welshman Craig Bellamy put City 2-1 ahead six minutes into the second half with an angled shot after a driving run, before Chelsea's Juliano Belletti was sent off in the 75th minute after tripping Gareth Barry in the box, allowing Tevez to make it 3-1 from the penalty spot.
Michael Ballack was then dismissed for a tackle from behind on Tevez before Bellamy tapped in at the far post after a quick break from former Chelsea winger Shaun Wright-Phillips, with the home side's nine men really stretched.
Frank Lampard scored a second of the game with a penalty of his own in injury time, but it was not enough.
Chelsea's loss was Arsenal's gain, with the Gunners dragging themselves right back in to the title race when they came from behind to win 3-1 at the Britannia Stadium in Saturday's late kick-off - Stoke's first defeat of 2010.
HORRIFIC INJURY
However, Arsenal's victory was overshadowed by what looked a horrific injury to Wales midfielder Ramsey who was taken straight to hospital with a suspected broken leg after a challenge from Potters defender Ryan Shawcross that earned the 22-year-old a red card.
The reaction of the players was reminiscent of that following Eduardo da Silva's infamous leg break against Birmingham City two years ago last Tuesday.
Danny Pugh had put Stoke ahead but a header from Nicklas Bendtner, a penalty by Cesc Fabregas and a tap-in from Thomas Vermaelen in stoppage time gave Arsenal the points.
Chelsea stay top with 61 points from 28 matches, one ahead of Manchester United (60) who meet Aston Villa in the League Cup final on Sunday. Arsenal are third on 58 points.
Manchester City have 49 points in fourth spot, one place above Tottenham Hotspur (46) who play Everton on Sunday.
TRAUMATIC WEEK
