Costa continues hot start in win
Diego Costa continued his remarkable start to life in the Premier League as Jose Mourinho celebrated his 250th match as Chelsea boss with a 3-0 defeat of Aston Villa.
Oscar put the Blues in front after seven minutes before Costa, selected despite his troublesome hamstring limiting him to one game a week, headed in after 59 minutes.
It was the Brazil-born Spain striker's eighth goal in his first six Premier League games, a tally second only to Micky Quinn's 10 with Coventry 22 years ago.
The clinical streak seems, initially at least, to fully justify the £32million Chelsea paid Atletico Madrid in the summer, although Costa also missed chances against a stubborn Villa.
A third Chelsea goal came from Costa's saved shot as Willian netted before the Spain striker was taken off in the hope he can recover in time to feature in Tuesday's Champions League Group G clash at Sporting Lisbon.
Villa began the day in third, three points behind leaders Chelsea, who reverted to 10 of the side which began last Sunday's draw at Manchester City.
Only three were retained following the midweek Capital One Cup defeat of Bolton in Gary Cahill, Cesar Azpilicueta and Oscar, who took the place of Ramires (groin) from the City starting side.
The Brazil playmaker broke the deadlock after Branislav Ivanovic freed Willian down the right.
Willian's shot was saved by Brad Guzan but only came back to the Brazilian, who pulled the ball back for his compatriot to slot in.
It had been a lively opening, fast-paced with a few contested decisions which saw Paul Lambert and his assistant Roy Keane glared at by a surly Mourinho.
There is recent history between the teams, with March's 1-0 loss at Villa Park key in Chelsea's title challenge unravelling last term.
This season the Blues have been reinforced and begun with ambitions of a first Premier League title since 2010.
There was ambition in abundance as they set about continuing their unbeaten start at the top of the table.
A deflected Willian effort hit the side netting while Cesc Fabregas asserted his authority on proceedings in midfield, playing the quarterback role, threading passes dangerously but not quite beating the Villa defence.
Chelsea have looked imperious going forward this term but had just one clean sheet in seven games entering the Villa clash and the visitors created moments of alarm.
Aly Cissokho hooked wide from a corner and Cahill hauled down Gabriel Agbonlahor inside his own half to earn a booking against his former club.
It was an indication of how concerned Chelsea's rearguard were about the pace which Villa possess.
Chelsea continued to have the better of the play but were unable to fashion chances until Fabregas dragged a shot wide from the edge of the area following a pass from Oscar.
Costa then saw his header from Willian's cross saved by Guzan and Ivanovic headed over from Fabregas' corner.
Fabian Delph had a shot blocked then fired over from 25 yards before Willian twice blasted high and wide for the Blues.
Delph fired wide from 25 yards after the restart and Nathan Baker headed on to the roof of the net from Ashley Westwood's free-kick as Villa threatened again.
Chelsea's danger was ever-present, though, particularly through Costa.
The Spain striker headed straight at Guzan from Ivanovic's cross before taking advantage of neat interplay on the left.
Eden Hazard and Willian played a one-two and the Belgian flicked the ball back to Azpilicueta, whose pin-point cross was converted by Costa.
A third, and a second for Oscar, so nearly followed when the ball broke for the Brazilian off Baker, but Cissokho scrambled it off the line.
Costa then glanced a header wide from a cross by Hazard, who was then brought off for World Cup winner Andre Schurrle.
The striker was influential in Chelsea's third after receiving a pass from Fabregas.
His shot was saved by Guzan but Willian bundled the ball in to seal an emphatic fifth win from six games this term.