The Spain international converted the all-important winner as the Blues momentarily moved nine points clear at the top of the Premier League table
Chelsea equalled their longest Premier League winning run by beating Crystal Palace 1-0 on Saturday for their 11th consecutive victory.
The league leaders were already guaranteed to be top of the tree at Christmas and a first-half goal from Diego Costa extended a run that stretches back to October 1.
Chelsea last won 11 on the bounce during their 2009-10 title-winning season and have been crowned champions each time they have previously topped the table on Christmas Day.
Costa’s opener came at the end of a drab first half but marked a sparkling return to form for the Spain international, whose 13th Premier League goal of the season takes him beyond his tally for the entire 2015-16 campaign.
He got his head to an excellent Cesar Azpilicueta cross to get the better of Palace goalkeeper Wayne Hennessey two minutes from the break, proving enough to secure maximum points.
Chelsea’s joy at moving nine points clear of Liverpool and Arsenal at the summit was tempered somewhat by yellow cards for Costa and N’Golo Kante, who are now suspended for the Boxing Day clash with Bournemouth.
Cesc Fabregas’ winning goal at Sunderland in midweek was not enough for him to retain his place in the Chelsea starting XI, dropping to the bench in one of two changes made by Antonio Conte.
Willian – one of the men to come in – was central to the visitors’ first meaningful attack.