It was a poor first 45 minutes from the Blues, who named a strong lineup but failed to dominate their Championship opposition. Raheem Sterling had an shot comfortably saved and Cole Palmer's scooped effort trickled wide, but that was as close as they came to opening the scoring.
Preston continued to frustrate Chelsea as the match moved towards the hour mark, until three goals in the space of 11 minutes gave the hosts complete the control and effectively put the match to bed.
Malo Gusto whipped a brilliant ball into the box and Armando Broja, quiet until that point, flicked a header into the far corner. The striker could have had a second almost immediately, but found the top of the bar with a header.
Thiago Silva was introduced and he swiftly got on the scoresheet, powering home a header from a corner, and two became three when Sterling whipped a free-kick over the wall and beyond Freddie Woodman.
Chelsea had the ball in the net for a fourth time late on, when Enzo Fernandez turned it in at the back post, though the offside flag was raised. The goal was eventually given though, a long VAR review deeming that the midfielder had kept himself onside, as the Blues ultimately cruised into the next round.
Mauricio Pochettino's side have now won three matches on the bounce, and turn their focus to a two-legged Carabao Cup semi-final against Middlesbrough.
