London: 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.

Manchester City 'keeper Joe Hart fails to stop Diafra Sakho’s header from crossing the line at Boleyn Ground on Saturday. Pic/Getty Images
Manchester City 'keeper Joe Hart fails to stop Diafra Sakho’s header from crossing the line at Boleyn Ground on Saturday. Pic/Getty Images  

Manuel Pellegrini's team, who kicked off in second place, had hoped to close the gap on the Blues to two points ahead of their rivals' clash with Manchester United on Sunday.

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 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 he 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 the south coast club leapfrog City into second place.

Fresh from last week's 8-0 home thrashing of Sunderland Ronald Koeman's side scored only one goal at St Mary's this match when Senegal winger Sadio Mane followed up in the 33rd minute after Graziano Pelle's shot came back off the post.