Manchester City's bid to put pressure on Premier League leaders Chelsea suffered a setback as the champions slumped to a surprise 2-1 defeat at West Ham on Saturday.
Manuel Pellegrini's team had hoped to close the gap on the Blues to two points ahead of their rivals' clash with Manchester United on Sunday. (Also read: Sanchez double for Arsenal downs Sunderland)
But West Ham maintained their impressive recent form to stun the visitors, who were beaten in the league for the second time this season following their loss to Stoke in late August.
Morgan Amalfitano opened the scoring in the 21st minute and Diafra Sakho added the decisive second goal in the 75th minute.
David Silva set up a tense finish when City's Spanish forward scored a fine individual effort two minutes later, but fourth-placed Hammers held on for a fourth win in their last five matches.
Later on Saturday, Southampton's 1-0 win at home to Stoke saw them leapfrog City into second place.
"We had a lot of chances to score but it is difficult to win if you don't take them," Pellegrini said.
"We have 80 points left to play for...We will continue fighting because there is no title being handed out at the moment," the City manager added.
For West Ham this was their first win in 11 games against City and midfielder Alex Song said: "The spirit is high and we are really enjoying it."
- Mane answers Saints' prayers -
Meanwhile Southampton's stunning start to the season continued against Stoke.
Fresh from last week's 8-0 home thrashing of Sunderland -- their record win in the English top flight -- Southampton scored only one goal at St Mary's on Saturday when Senegal winger Sadio Mane followed up in the 33rd minute after Graziano Pelle's shot came back off the post.
"We will enjoy being second because it isn't normal, because there are other teams with maybe more qualities," said Southampton manger Ronald Koeman.
"But the team deserves this position because they work hard every day," the Dutchman added.
Sunderland conceded just two goals on Saturday but both were from defensive errors as Alexis Sanchez's double saw Arsenal to a 2-0 win at the Stadium of Light.
Sanchez struck in the 30th minute following a poor back pass by Wes Brown and then latched on to a 'gift' clearance from former Gunners keeper Vito Mannone in the closing seconds.
"I'm sure everybody will comment on the two goals but we tried hard, the players gave everything," said Sunderland boss Gus Poyet. "We did not create enough but you cannot concede goals like we did today."
Liverpool, fresh from their thumping 3-0 Champions League loss at home to holders Real Madrid in midweek, were held to a goalless draw by Hull at Anfield.
Underfire Reds striker Mario Balotelli, who could have scored with the last kick of the game, was left with a return of just one goal in 11 appearances since his £16 million ($26 million, 20 million euros) move from AC Milan.
"After a tough game in midweek it was a great effort from the players and we deserved to win the game," said Liverpool manager Brendan Rodgers.
As for Balotelli's late chance, Rodgers added: "He will be disappointed with that. It was a perfect ball, he just opened his foot up too far and the chance was gone."
Crystal Palace squandered a 2-0 lead in a 2-2 draw away to West Bromwich Albion.
Brede Hangeland put Palace ahead in the 16th minute at the Hawthorns before Mile Jedinak doubled the London club's lead with a penalty at the end of the first half after Yannick Bolasie was brought down in the box.
But the Baggies hit back in the 51st minute when half-time substitute Victor Anichebe headed in from a corner before Saido Berahino rescued a point in stoppage-time with a penalty after Jedinak fouled Anichebe.
Ivory Coast striker Wilfried Bony scored either side of half-time as Swansea beat Leicester 2-0 at the Liberty Stadium in Saturday's late kick-off.
Sunday sees Chelsea looking to move six points in front at Old Trafford as Tottenham face Newcastle and Everton travel to strugglers Burnley.
Bottom-of-the-table Queens Park Rangers are at home to Aston Villa on Monday.