London - Premier League leaders Chelsea showed West Ham United no Christmas cheer on Friday with a one-sided 2-0 Boxing Day victory that enhanced their status as title favourites.
Goals in each half from John Terry and Diego Costa - his 13th of the campaign - earned Jose Mourinho's side a win that enabled them to open up a provisional six-point lead over second-place Manchester City.
Fourth-place West Ham were expected to provide a stern test after a run of five games without defeat, but despite hitting the woodwork late on, Sam Allardyce's team were well beaten in what was the London rivals' 100th encounter.
"We played a very good game against a very difficult opponent. When we scored, we had the game always under control," Mourinho told Sky Sports.
"I am really happy. We are doing very well."
Eden Hazard overcame a knock to start for Chelsea and he proved a bewitching presence as the hosts swarmed all over their opponents from the start at Stamford Bridge.
Oscar had gone close and visiting goalkeeper Adrian had parried from Gary Cahill and Willian by the time Terry broke the deadlock in the 31st minute, tapping in after Costa headed on Cesc Fabregas's corner.
West Ham spent long periods of the first half penned inside their own area, with Adrian producing a one-handed save to thwart Nemanja Matic and Costa shooting over from a Branislav Ivanovic cross.
After Adrian had thwarted Hazard, Costa made it 2-0 in the 62nd minute, gathering a pass from Hazard and sending Carl Jenkinson and James Collins the wrong way before drilling a left-foot shot into the bottom-right corner.
Adrian athletically tipped an Oscar free-kick over the bar and Fabregas curled wide, but although Chelsea had dominated, West Ham came close to snatching a goal when substitute Morgan Amalfitano dinked a shot against the post.
Defending champions City will bid to close back to within three points of Mourinho's men later on Friday when they visit West Bromwich Albion, while third-place Manchester United host Newcastle United.
The traditional Boxing Day schedule means that all 20 English top-flight clubs are in action on the same day for the first time this season.