London (AFP) - Chelsea showed why they are the Premier League leaders with a comprehensive 2-0 dismissal of London neighbours West Ham United in Friday's early Boxing Day fixture.
John Terry and Diego Costa were the men on target as Jose Mourinho's side moved six points ahead of second-place Manchester City, who are in action later in the day.
West Ham had begun the day in fourth place, but the gulf in class between the two teams was apparent throughout, with Chelsea's Eden Hazard the game's most eye-catching performer.
Andy Carroll volleyed wide in the first minute as West Ham -- criticised by Mourinho for their defensive tactics in the 0-0 draw at Stamford Bridge last season -- indicated they might be more ambitious this time.
There was a much better chance for Chelsea soon after when the West Ham defence failed to deal with a cross from Willian that found Oscar, but the recalled Brazilian blasted over with only goalkeeper Adrian to beat.
Gary Cahill then headed over from a delivery into the box by fellow centre-back Terry as Chelsea continued to dominate the opening exchanges.
There was a nervous moment for the visitors when Hazard pushed the ball between Winston Reid's legs and went down on the edge of the box when the defender made contact, but referee Michael Oliver allowed play to continue.
Enner Valencia fired a West Ham free-kick over, but Adrian was soon required to make a save at the other end as Cahill let fly from close range at the near post.
James Collins was the first man into the book for a tackle on Costa in full flight, despite the defender rightly claiming he had played the ball.
Oscar had previously fired one wide, so it was Cesc Fabregas who took the free-kick, which he fired at Adrian.
- Amalfitano hits post -
Willian did the same from open play as Chelsea continued to exert immense pressure on the West Ham defence, and this time Adrian could only parry.
A goal was coming and it was Terry who provided it in the 31st minute, side-footing home from a couple of yards out after Costa had headed on a Fabregas corner.
Chelsea continued to move the ball about speedily and Adrian had to dive to keep out a low drive from defensive midfielder Nemanja Matic before Costa's deflected effort spun just wide.
Tempers flared just before half-time when West Ham's players reacted angrily to what appeared to be a dive inside the area by Branislav Ivanovic, who went to ground near Carroll.
West Ham began the second half with a flurry of activity, but could not fashion a clear chance, and it was not long before Adrian had to parry a fierce drive from Hazard that almost knocked him off his feet.
The visitors made a double change just before the hour mark, with Carroll and Mark Noble replaced by Diafra Sakho and Alex Song, but Chelsea's response was a second goal.
West Ham lost possession on the half-way line, Hazard found Costa, and the striker found the bottom-right corner despite the presence of three defenders to register his 13th effort of the campaign.
Costa then volleyed a difficult chance wide after goalkeeper Thibaut Courtois, who had hardly been involved, had to gather at the feet of Sakho at the other end.
Adrian continued to prevent a rout, tipping over an Oscar free-kick and thwarting Matic from the ensuing corner.
A chance to get West Ham back in the game came Valencia's way 12 minutes before the end, but the Ecuador forward lashed his shot wide from an inviting position in the box and it was a similar story when substitute Morgan Amalfitano headed wide.
There was still time for Amalfitano to spurn an even better chance, the midfielder hitting the post after darting between Cahill and Terry.