Blues maintain momentum
Chelsea followed up their Capital One Cup victory with a hard-fought 1-0 win on their return to Barclays Premier League business at West Ham.
Jose Mourinho won a first trophy of his second spell as Blues boss with a 2-0 win over Tottenham on Sunday and Chelsea remain well placed to add a first Premier League title in five years.
The Hammers had one win in 17 against the Blues entering the contest but refused to be cowed by the leaders and deserved more, only for Eden Hazard's first-half header to settle the contest, keeping Chelsea five points clear of second-placed Manchester City.
Mourinho spoke of short celebrations after the Wembley win and captain John Terry insisted they had been postponed until the end of the season, when he hoped there would be further cause to party.
Yet at times it appeared as though Chelsea's defenders had a hangover as the pace of Enner Valencia, Diafra Sakho and Stewart Downing found holes.
Terry was booked for pulling down Valencia in the first half and cautious thereafter, with Chelsea indebted to a number of fine saves from the restored Thibaut Courtois - namely from Cheikhou Kouyate and Sakho - as the Hammers pressed forwards.
Ramires struck a post on the counter-attack and had a header well saved by Adrian, while Willian spurned a late chance for a second to settle the contest.
The Hammers now have one win in 11 league games to slip further down the standings - and Sam Allardyce appears to be running out of time to convince his bosses to extend his contract, which expires at the end of the season.
Chelsea's players, meanwhile, have two days off before resuming preparations for next week's Champions League last-16 second leg with Paris St Germain.
Courtois returned in place of Petr Cech and Oscar replaced Willian following Chelsea's win at Wembley as Mourinho made two changes, with Kurt Zouma continuing in midfield as Nemanja Matic completed his two-match suspension.
Kevin Nolan replaced Alex Song for the Hammers, who had to make a further change after seven minutes when Winston Reid limped off and James Collins came on.
Chelsea almost went in front while the Hammers were preparing to make the switch, but Diego Costa could only meet Oscar's cross with his shin and the ball went over.
Kouyate halted Costa as the striker bore down on goal and was then booked after catching Zouma with a flailing arm.
Terry was shown a yellow card after being caught flat-footed by Valencia, with the Blues skipper clearly concerned by the pace of the West Ham attack.
Courtois saved from Kouyate at close range before Chelsea struck when Cesc Fabregas fed Ramires down the right, he crossed and Hazard converted.
There was a hint of offside, but Hazard - shorter than the 5ft 8in he is credited as on the Chelsea website - got the benefit of the doubt and reacted with surprise at scoring with his head.
Costa was looking to end a five-match scoring drought and should have done so when played through by Hazard, but Carl Jenkinson made a fine last-ditch tackle as the striker shaped to shoot.
Jenkinson next showed his attacking ability, crossing for Sakho, but Courtois made a fine reflex save.
Chelsea's defensive jitters continued in the second half.
Kouyate's mishit shot fell for Sakho, who turned Gary Cahill and shot just wide. Then Downing's cross from the left was missed by Cesar Azpilicueta, bounced off Terry and fell for Sakho, who s wung a leg at it and saw Courtois parry before Zouma cleared.
Chelsea were playing on the break and Ramires surged down the right after fine link-up play between Hazard and Costa.
The Brazil midfielder cut back on to his left foot but his shot came back off the inside of the post.
Ramires then had a header saved by Adrian, who was the quieter of the two goalkeepers.
Courtois saved from Sakho, yet again, after Downing fed the striker before the goalkeeper spilled a Valencia effort. The ball went to Sakho, but Cahill intervened, turning the ball behind for a corner.
Kouyate ran at the Chelsea defence and chased a return pass from Sakho but ran into Terry, stopping him in his tracks.
West Ham protested but Terry had already turned. Kouyate went off soon afterwards after treatment on his head.
The Hammers continued to forge forwards in search of an equaliser, but Sakho headed over Downing's cross.
Substitute Nene claimed handball against Cahill, who blocked his shot, but referee Andre Marriner dismissed the appeals.
Willian, on for Oscar, then spurned a chance for Chelsea's second, but the Blues did not need it.