The first half saw a fairly low-key display from the Blues, with Frank Lampard missing a couple of chances the like of which he normally feeds upon in and around the box, while Oscar should have opened the scoring after scuffing the ball against the post following a neat pass from Juan Mata.
It was Brentford, though, who almost stole the headlines of the first half, as they saw a goal harshly disallowed. Midfield man Adam Forshaw found himself tripped by David Luiz just outside the box, before Marcello Trotta skipped past the challenge of Gary Cahill and fired a low shot into the corner of the goal. The referee, though, had blown the whistle for the Luiz foul, and failed to play what would have been a sensible advantage.
The second half saw Chelsea step out with renewed purpose, and it didn't take long for the deadlock to be broken. As has so often been the case this season, it was Mata who dragged the Blues out of potential trouble, the Spaniard firing in from 20 yards with a low effort that left Simon Moore in the Brentford goal with no chance of making a save.
The floodgates then opened for the Blues, Oscar finishing with a cheeky little back heel from around the penalty spot after a neat assist from Branislav Ivanovic, before Lampard, now his club's all-time top goalscorer in this competition, powered home his 199th goal for Chelsea with a clinical finish on the volley.
There was still time before the final whistle for John Terry to get in on the action, the defender nodding home at the far post after connecting with Oscar's deep cross to make the scoreline a flattering one for Chelsea, who now travel to Middlesbrough on February 27.