The Blues stretched their winning run in the Premier League to a staggering eleven games with their 1-0 success at Selhurst Park.
Diego Costa headed home in the first half and Antonio Conte’s side saw the game out to go nine points clear at the top of the table.
Pundit Hartson believes Chelsea should have scored more against Palace and hailed their superb defensive display.
“11 wins out of 11, magnificent form from Chelsea”
He told the BBC: “11 wins out of 11, magnificent form from Chelsea.
“The endeavour was there for Palace. It was only 1-0 but it could have been a lot, lot more.
“Defensively Chelsea were outstanding. 1-0 flattered Palace.”
Hartson believes Palace must hit back as soon as possible or they could face the drop this season.
He added: “Palace looked one dimensional at times.
“In the second half they were more direct into Benteke but you want more from Zaha, Puncheon and Townsend.
“Palace need to get back on track because they could be dragged into that relegation zone.”
Chelsea are at home to Bournemouth on Boxing Day while Crystal Palace face London rivals Watford.