Manchester City's bid for a second successive English Premier League title suffered a setback on Saturday, losing 1-2 to West Ham United.
Manchester City went into the match five points behind Chelsea, but in the next 24 hours, that gap could widen to eight points, depending on the outcome of Celsea's match against Manchester United on Sunday.
Morgan Amalfitano opened the scoring for City when he netted Enner Valencia's cut-back from three yards.
Sakho made it 2-0 for West Ham, before David Silva pulled one back for City, but ultimately it was too little, too late.