West Ham inflicted a second league defeat of the season on champions Manchester City's to consolidate their place in the top four.

Diafra Sakho's sixth goal in as many Premier League starts gave the Hammers a 2-1 victory - their fourth in five games - at Upton Park.

Morgan Amalfitano gave Sam Allardyce's men a deserved first-half lead and Sakho, signed from Metz in the summer, made it 2-0 with the assistance of the Goal Decision System.

A downward header by the Senegal forward, who went off with a shoulder injury, dropped over the line and was awarded after City goalkeeper Joe Hart had clawed the ball out inside the far post. David Silva hit back to set up a grandstand finale, but City missed the chance to narrow the gap to leaders Chelsea, who visit Manchester United today, and slipped behind Southampton into third place.

Allardyce was full of praise for the Frenchman and his strike partner Enner Valencia. He said: "I don't think they really know how good they have been. They have just come here, they want to play football and I don't think they realise what such a big impact they have made and the rest of the team has been lifted by those two.

"We have goalscorers, we have players who believe they are going to score, none more than Sakho who has scored yet again today."

Southampton, 8-0 winners over Sunderland last weekend, climbed to second, three points behind the Blues, with a 1-0 win over Stoke at St Mary's Stadium.

Sadio Mane tucked in the rebound after Graziano Pelle's strike hit the woodwork and it was enough to give Ronald Koeman's men seven wins in eight games in all competitions, the only blip coming at Tottenham earlier this month.

Sunderland were unable to respond positively to the thrashing by Saints as Arsenal won 2-0 thanks to more calamitous defending.

Alexis Sanchez punished mistakes by Wes Brown and then keeper Vito Mannone to give the Gunners just a third league win of the season and take Arsene Wenger's men to fifth place.

Mario Balotelli missed a late opportunity as Liverpool endured a frustrating goalless draw with Hull.

The Reds are sixth, while Hull, who extended their unbeaten run to three games, are ninth.

West Brom came from two goals down at half-time to draw 2-2 with Crystal Palace after Saido Berahino's stoppage-time equaliser from the penalty spot.

Brede Hangeland and Mile Jedinak's penalty put the Eagles in front, but Victor Anichebe pulled a goal back and visiting goalkeeper Julian Speroni went off with a head knock.

The delay to treat Speroni resulted in six minutes of stoppage time and Berahino converted from the spot after Anichebe had been fouled by Jedinak.

Wilfried Bony scored both goals as Swansea saw off Leicester 2-0 at the Liberty Stadium in the late kick-off.

The Ivory Coast striker made it four goals in three games with one in each half against the shot-shy Foxes.