Chelsea maintained their four-point advantage at the top of the Premier League - despite a 1-0 loss at Manchester City - as Arsenal slumped to a shock 3-2 home defeat to West Bromwich Albion.
Carlos Tevez condemned Chelsea to their first league defeat of the season at Eastlands, striking on the hour mark to score for the fifth-successive game against the Blues.
After a tense first half devoid of many real chances, Tevez fired Roberto Mancini's side ahead in the 59th minute after a Chelsea move had broken down. City broke quickly and David Silva's ball from the left found the Argentina international, who ran wide of Ashley Cole and drilled his low shot past Petr Cech.
But Arsenal were unable to capitalise on City's win as they were stunned at Emirates Stadium by West Bromwich Albion. The surprise 3-2 defeat has ended the Gunners' unbeaten start to the season - and dealt a huge blow to their title hopes ahead of a trip to Stamford Bridge next weekend.
Arsene Wenger's side appeared to have earned themselves a reprieve when Manuel Almunia saved Chris Brunt's first-half penalty, but the visitors claimed the lead early in the second period as Peter Odemwingie tapped in from close range after fine work from former Arsenal winger Jerome Thomas.
Shortly afterwards, West Brom took a huge step towards a first Premier League victory away from home in 19 attempts when a calamitous error from Almunia allowed Gonzalo Jara's shot to slip into the net. Thomas appeared to have put his side out of sight when he made it 3-0, before Samir Nasri - in for the injured Cesc Fabregas - pulled two late goals back for the hosts.
Liverpool's difficult week continued as they were forced to settle for a disappointing 2-2 draw at Anfield against Sunderland. Coming off the back of a humiliating Carling Cup reverse against Northampton, the Reds powered into an early lead as Dirk Kuyt latched onto Michael Turner's weak backpass - the defender thought the ball had gone dead for a free-kick - to rifle home.
But a brace of strikes from Darren Bent turned the game on its head, before Steven Gerrard rode to his side's rescue with his first league goal at Anfield since February.
The pressure was eased on West Ham United boss Avram Grant as he led his team to a vital 1-0 victory over Tottenham Hotspur at Upton Park, with a strike from Frederic Piquionne - his second of the week - handing the Hammers a first league triumph of the season.
No such respite for David Moyes, whose Everton side are still without a win from their six Premier League games to date after being held to a 0-0 stalemate against Fulham at Craven Cottage. Despite controlling the game Everton were unable to pierce the unbeaten Cottagers' stubborn defensive line.
Birmingham City extended their unbeaten home record in the Premier League to beyond a year with a 0-0 draw against Wigan Athletic, while a last-gasp goal from Brett Emerton handed Blackburn Rovers a 2-1 win over Blackpool at Bloomfield Road.