The match is of high importance for Chelsea despite the race for top four being all but over for Antonio Conte's side, with them eight points behind Tottenham Hotspur with just seven games remaining. But Javier "Chicharito" Hernández rescued a point for West Ham, slotting low shot past Thibaut Courtois and several Chelsea bodies easily.
He did say that Javier Hernandez would be available for the 4.30pm kick-off.
While he has only scored twice against Chelsea in 10 appearances, his goal last December stunned the Blues into a 1-0 defeat and West Ham fans will hope of a repeat performance from their season's best player.
The win over Saints not only lifted West Ham clear of the drop zone, it also lifted the mood around the whole club following the protests and pitch invasions which marred their previous match against Burnley.
Chelsea took the lead from an unlikely source as Cesar Azpilicueta scored from a corner.
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The Tall Blacks lost what should be a gold medal preview game, going down 79-73 to Australia in the men's basketball group game. Guy, who won the bronze medal in the 400m freestyle final on Thursday, is expected to be fit for the rest of his events.
The half ended with the home side leading by a single goal. Lanzini might not have hit the heights of last season, but he has still contributed three goals and six assists in his 21 league games.
Both teams have become over-reliant on their respective key creative player this season, however, they will once more be needed to provide an edge to their attacks.
Chelsea's persistent pressure eventually paid off thanks to Azpilicueta who prodded the ball home from close range after Morata headed back across goal from a corner.
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A quick pass from Arnautovic found Hernandez and the striker, on for just three minutes, drilled a fine finish past Thibaut Courtois.