Manchester United suffered more misery when they lost 2-1 at home to West Bromwich Albion on Saturday in their worst start to a Premier League season with the champions in the bottom half of the table after six games.
Morgan Amalfitano and Saido Berahino scored for the visitors either side of a Wayne Rooney leveller at Old Trafford to leave United in 12th place a week after they suffered a crushing defeat at local rivals Manchester City.
City also suffered a surprise reverse at Aston Villa, who scored three second-half goals to win 3-2, leaving Tottenham Hotspur top of the standings after their 1-1 draw with Chelsea at White Hart Lane earlier on Saturday.
John Terry headed a second-half equaliser for Chelsea as the managerial battle between Portuguese managers Jose Mourinho and his former apprentice Andre Villas-Boas ended in stalemate.
Southampton's watertight defence held firm as they climbed to fourth with a 2-0 victory at home to Crystal Palace, Hull City won 1-0 against visiting West Ham United and Cardiff City triumphed 2-1 at struggling Fulham.
Arsenal can return to the summit if they beat Swansea City away in Saturday's late kickoff.
Manchester United might have thought they had exorcised last weekend's crushing 4-1 reverse at City by beating arch rivals Liverpool in the League Cup third round in midweek, but the demons returned against West Brom.
The defeat will heap further pressure on manager David Moyes, whose every decision has been under the microscope since he replaced Alex Ferguson in the close season.
"You're always going to have bad results," Moyes told the BBC. "It is how you deal with them. There are lots of games to come and it's about how you deal with them, so we look forward to them."
United's failure to turn possession into chances again came back to haunt them, while they continued to look suspect at the back.
The two goals they conceded against West Brom came straight from the top drawer and Amalfitano's effort nine minutes into the second half was a moment of individual brilliance.
Picking up possession on the halfway line, he rode a Michael Carrick challenge, put the ball