West Ham 1 Chelsea 2: Hazard and Costa on target as leaders breeze to derby success
Chelsea continued their relentless march towards the Premier League title with a controlled 2-1 win over West Ham at London Stadium.
A much-changed Blues XI were knocked out of the EFL Cup at the same ground in October but Antonio Conte's men were all business this time around.
They absorbed early pressure without coughing up chances and Eden Hazard displayed the devastating, clinical edge West Ham lacked as he scythed through them for a counter-attacking opener.
Conte's side carried menace on the break throughout, although their second came courtesy of poor set-piece defending from Slaven Bilic's side, with Diego Costa needing no second invitation to collect his 18th goal of the season after 50 minutes.
Manuel Lanzini grabbed a late consolation for the Hammers, who remain just outside the top-10, as he rifled home his sixth league goal of the season.
But Chelsea were not to be denied and sit 10 points clear of Tottenham at the summit, although their lead will be cut to eight if Manchester City win their game in hand at home to Stoke City on Wednesday.
Running repairs were the order of the day during the opening stages as West Ham striker Andy Carroll suffered a bloodied nose in an aerial challenge with Victor Moses and Chelsea defender Gary Cahill needed to replace a torn shirt.
West Ham pressed the league leaders back without crafting a goalscoring opportunity before being clinically unpicked on the counter-attack after 26 minutes.
Mark Noble's pass was cut out by N'Golo Kante and Hazard seized upon the opportunity - tearing forward from his own half, exchanging passes with Pedro and accelerate past goalkeeper Darren Randolph to slot home.
Worrying scenes followed as an angry West Ham got on to the field to confront the celebrating Chelsea players, before being led away by security.
Hammers playmaker Lanzini made a similarly darting run towards a more well-manned Chelsea defence but blazed over after a one-two with Noble.
The hosts somehow escaped falling two behind in the 42nd minute when Diego Costa missed his kick from Hazard's low cross, Moses saw his follow-up bravely blocked by Aaron Creswell and Randolph saved from Pedro on the rebound.
But Chelsea had their second within five minutes of the restart as Pedro Obiang could only glance on Cesc Fabregas' corner for Costa to bundle in from close range.
A deft piece of skill from Marcos Alonso saw him breeze past Jose Fonte - continuing a torrid outing for the West Ham centre-half - but the wing-back prodded just past Randolph's far post.
The hosts' willingness to hurl balls into the Chelsea box almost paid off in the 61st minute as Thibaut Courtois saved with his legs from Sofiane Feghouli and Robert Snodgrass headed over.
Randolph remained the more threatened goalkeeper and the Republic of Ireland international reacted superbly to tip around the corner after Costa turned masterfully to get a shot off inside the box.
West Ham kept plugging away commendably for a side safely ensconced in mid-table and gained some consolation when Lanzini latched on to a loose ball and thrashed past Courtois in stoppage time.
Chelsea, with an FA Cup quarter-final against Manchester United next on the agenda, have their sights firmly trained upon the double.