Kai Havertz’s brace secured a 2-0 win over Fulham on Saturday.
The £71million signing netted either side of half-time to move the Blues six points clear of fifth-placed West Ham, who play Burnley on Monday.
Meanwhile, Fulham remain nine points from safety with their closest rivals Newcastle hosting Arsenal on Sunday.
The Cottagers started brightly as Antonee Robinson’s long-range shot was tipped over the crossbar by Edouard Mendy.
Scott Parker’s side found themselves behind in the 10th minute when Mason Mount excellently controlled a long Thiago Silva pass to play Havertz through on goal.
And the German calmly finished past Alphonse Areola to break the deadlock.
With Chelsea struggling to create chances, they had Mendy to thank for keeping their lead intact at half-time.
Ademola Lookman tested the goalkeeper with a low effort, before the Senegal international did well to save a deflected Ola Aina just before the break.
Despite ending the first-half strongly, Fulham were 2-0 down within four minutes of the restart.
A smart one-two between Timo Werner and Havertz resulted in the latter completing his brace.
Havertz doubled his Premier League tally to four goals in just one match with the midfielder flourishing under Thomas Tuchel.
Chelsea had an injury scare when Mount stayed down after a painful-looking fall, but he was able to play on before being replaced by Tammy Abraham with 14 minutes to go.