London - Manchester United moved three points clear at the English Premier League summit after beating Reading 4-3 in a remarkable game on Saturday, which was to prove a day of despair for Chelsea and Arsenal.
All the goals came before half-time at the Madejski Stadium, equalling the Premier League record for first-half goals, as United overcame their defensive frailties to draw away from Manchester City - held 1-1 by Everton - ahead of next weekend's Manchester derby.
Chelsea are now 10 points off the pace in third place after seeing their run without victory stretch to seven games in a 3-1 defeat at West Ham United, while Arsenal tumbled to 10th after a 2-0 loss at home to Swansea City.
A Wayne Rooney penalty put United 2-1 up in the 16th minute at Reading after Anderson had cancelled out Hal Robson-Kanu's eighth-minute opener for the hosts, only for headers from Adam Le Fondre and Sean Morrison to restore the home side's lead.
However, Rooney tucked away Patrice Evra's cross to equalise in the 30th minute before Robin van Persie put Alex Ferguson's men back in front moments later by finishing from Rooney's flick.
Van Persie had a goal ruled out before half-time despite the ball appearing to cross the line and then blazed wide of an open goal in the second half after an error from Reading goalkeeper Adam Federici, but 4-3 proved enough.
Chelsea's match at West Ham was another game of two halves.
The visitors led 1-0 at half-time, only for the hosts' rousing second-half fightback to condemn the European champions to their longest sequence of top-flight games without victory since 1995.
Juan Mata scored the first goal of the Rafael Benitez era to put Chelsea ahead at Upton Park but a revitalised West Ham roared back to prevail through goals from Carlton Cole and substitutes Mohamed Diame and Modibo Maiga.
"At this level, you have to take your chances, and we had many clear chances to finish the game," said interim coach Benitez, who has picked up two points from a possible nine since replacing the sacked Roberto Di Matteo.
Michu was Arsenal's scourge at the Emirates Stadium, the £2m signing from Rayo Vallecano claiming a late brace for Swansea to leave Arsene Wenger's side five points below the top four.
"We were not good and Swansea deserved to win," said Wenger, whose side have made their worst start to a league season since he arrived in 1996.
"Our fans cannot be happy when we do not win games and what we produced today is not enough to keep our fans happy."
Marouane Fellaini put Everton ahead in the 33rd minute at City, following in after Joe Hart parried his header, but the Belgian's foul on Edin Dzeko allowed Carlos Tevez to bring the champions level from the spot before half-time.
"It was a hard game," City manager Roberto Mancini told the BBC.
"We tried to break them down but this week we have played three games in six days so we are tired. We also have players injured."
A 75th-minute goal by Dean Whitehead gave Stoke City a 1-0 win at West Bromwich Albion, and Tottenham Hotspur capitalised on the Baggies' setback to move into fourth place with a 3-0 win at Fulham.
Brazilian holding midfielder Sandro set Spurs on their way with a wickedly swerving 30-yard effort in the 55th minute, before a quick-fire Jermain Defoe brace took the game away from Martin Jol's side.
Spurs lost both Michael Dawson and the in-form Gareth Bale to injury, but coach Andre Villas-Boas said: "They are not very serious (injuries) and hopefully we will have them both back soon."
Harry Redknapp's home debut as Queens Park Rangers manager ended in stalemate after the top flight's bottom club were held 1-1 by Aston Villa at Loftus Road.
Brett Holman put Villa ahead in the eighth minute but Jamie Mackie's fine 18th-minute header levelled the scores for QPR, who had Stephane Mbia taken to hospital following a collision with Gabriel Agbonlahor.
Liverpool climbed one place to 11th after Daniel Agger's 43rd-minute header secured a 1-0 success at home to Southampton that gave Brendan Rodgers' side only their third home win of the campaign.