Chelsea were made to dig deep as they maintained their five point lead at the top of the Premier League with a hard-fought 1-0 victory at West Ham.

The Blues overcame a stern test of their title credentials thanks to Eden Hazard’s first-half header and a string of fine saves from goalkeeper Thibaut Courtois.

West Ham pressed forward all night but could not find the breakthrough as Jose Mourinho's men defended resoulutely, needing crucial interventions from the imperious Courtois and then Gary Cahill as the Blues survived a late onslaught to take all three points back across London.

Mourinho, who has never tasted defeat at West Ham made just two changes to his Capital One Cup-winning side for the trip to Upton Park with Courtois and Oscar starting but it was West Ham, who lost Winston Reid to injury in the eighth minute, looking the more likely to break the deadlock in the opening stages.

Kevin Nolan was brought in to replace Alex Song for the hosts and he was instrumental in creating West Ham’s first chance in the 18th minute, but Cheikhou Kouyate’s shot was smartly saved by the onrushing Courtois.

West Ham were causing John Terry, who was booked for pulling back Enner Valencia, and Cahill plenty of problems but could not take advantage as Diafra Sakho mis-kicked Kouyate’s pass when shooting from inside the penalty area.

Despite looking the more likely West Ham switched of for a split second and were punished as Hazard ghosted in unmarked behind the Hammers defence to head Ramires’ cross past Adrian from five yards out in the 22nd minute.

The goal drew the sting out of the home side and they were caught napping again as Hazard released Diego Costa on goal but just as he was lining up his shot, Carl Jenkinson recovered to make an excellent last-gasp tackle.

Minutes later, Jenkinson was in the thick of the action again but this time at the other end. The on-loan full-back whipped in an excellent cross from the right to find Sakho, but the striker headed the ball straight at a thankful Courtois.

West Ham continued to test the Chelsea back four after the break, however, and when they managed to beat Terry and his troops, they could not get past Courtois, who got his fingertips to Sakho’s close range shot.

The visitors thought they had wrapped up all three points as Ramires cut back on his left foot in the penalty area, but his shot rebounded off the post and into the grateful arms of Adrian.

The Brazilian had another chance to extend the Blues’ advantage minutes later but this time it was Adrian with the heroics as he saved the header with his legs.

However, in a pulsating game in east London, it was West Ham who were piling on the pressure late on as Downing breezed past Branislav Ivanovic to pick out Sakho, but he failed to direct his free header on target.

Chelsea were dropping deep in attempt to soak up the pressure but it nearly back-fired when Courtois made his only error of night, spilling the ball to Sakho, but it was not to be for the Senegal international as Cahill intervened.

Substitute Willian had one final chance to wrap things up for the league leaders in the dying stages but Aaron Cresswell managed to clear off the line, while at the other end Nene's shot was well blocked by Terry to typify Chelsea's defending on the night.

The Hammers now have one win in 11 league games and have slipped to 10th in the standings but for Chelsea, it is a crucial win to stay five points clear of Manchester City with a game in hand.

Mourinho can now focus on next week's Champions League last-16 second leg with Paris St Germain safe in the knowledge his side are in an excellent position to add the league title to Sunday’s Capital One Cup success.

Player ratings

West Ham: Adrian (7), Jenkinson (7), Tomkins (7), Reid (5), Cresswell (7), Noble (6), Kouyate (8), Nolan (6), Downing (6), Valencia (6), Sakho (5).

Subs used: Collins (6), Nene (5).

Chelsea: Courtois (9), Ivanovic (7), Cahill (7), Terry (8), Azpilicueta (7), Ramires (7), Zouma (7), Fabregas (6), Oscar (5), Hazard (8), Costa (7).

Chelsea subs: Willian (6), Drogba (5), Remy (5).

Man of the Match: Thibaut Courtois

Teams

West Ham United Adrian, Jenkinson, Tomkins, Reid (Collins 7), Cresswell, Noble, Kouyate (Nene 87), Nolan (c), Downing, Valencia, Sakho
Subs Not Used Jaaskelainen, Demel, O’Brien, Song, Jarvis
Booked Kouyate, Collins, Nolan
Goals

Chelsea Courtois, Ivanovic, Cahill, Terry (c), Azpilicueta, Ramires, Zouma, Fabregas, Oscar (Willian 74), Hazard (Remy 90+6), Costa (Drogba 90+3)
Subs Not Used Cech, Luis, Cuadrado, Loftus-Cheek
Booked Terry, Hazard, Fabregas, Drogba
Goals Hazard 22

Attendance 34,927

Referee Andre Mariner