Chelsea gave a ruthless display of finishing as four second half goals ended Brentford’s interest in the FA Cup with Budweiser.
Brentford were competitive for long stages of the Fourth Round Replay but fell behind nine minutes in to the second half and couldn’t respond.
Three goals in the final quarter, scored as Brentford chased the game, gave the score line a rather flattering look.
The match followed the pattern that was to be expected – Chelsea dominated possession and Brentford tried to contain them.
The hosts did not, however, press Brentford back continually, particularly in the first half, and they had a lot of the ball in areas that did not hurt The Bees.
When they did go through the gears, however, the class of a team that started the day as holders of the FA Cup and UEFA Champions League was apparent.
Brentford got to the break all square and, arguably, could have been ahead as Marcello Trotta had a goal rule out.
But once they fell behind, they could not find a way back.
Tony Craig blocked an early shot from Demba Ba and Branislav Ivanovic headed wide.
Juan Mata supplied that chance and was at the heart, along with Oscar, of everything Chelsea created.
Ba headed an Oscar cross wide and when Victor Moses escaped on the right, Frank Lampard missed his kick 12 yards out and Harlee Dean made a superb block to prevent Oscar scoring.
David Luiz also shot over for the hosts but Brentford were by no means defending exclusively.
Adam Forshaw, on the right of midfield, caused the hosts problems and shot narrowly wide from 20 yards when he had an early sight of goal.
Clayton Donaldson headed a Shaleum Logan cross wide and a Forshaw shot cannoned off Marcello Trotta when it may have been heading towards the bottom corner.
Chelsea should probably have been ahead by the half hour mark – Douglas made a vital block from an Oscar shot and Lampard sliced wide before Mata hit a ball across the face of goal and Ashley Cole, arriving late, fired it back where it had come from.
Oscar missed the best opening after Mata played a Victor Moses flick in to his path but the Brazilian fired a shot against the post from eight yards.
Douglas and Simon Moore combined to deny Ba but the Brentford goalkeeper had not been forced in to a save of note by the half hour mark.
Forshaw shot narrowly wide at the other end before Donaldson blocked a Lampard free kick.
The Bees had the ball in the net six minutes before the break through Trotta but referee Neil Swarbrick, who did not give Brentford a free kick until the 39th minute, had already blown up for a foul on Forshaw by Luiz.
Forshaw fired the free kick in to the defensive wall and the follow-up was blocked.
Tom Adeyemi had a shot deflected wide at the end of the first half but Lampard should have put the hosts ahead when he met an Ivanovic cross ten yards out but he shot wide.
Chelsea started the second half on the front foot and Moore made an early save from an Ivanovic header, pushing the ball just out of the path of Ba.
Craig made an important tackle when Moses escaped down the left, got in to the penalty area and tried to cut it back.
Lampard and Gary Cahill both had efforts blocked before Chelsea went ahead nine minutes in to the second half.
A long ball dropped loose after a challenge between Dean and Ba and Mata moved on to it before firing low past Moore and in to the corner from 25 yards.
Craig blocked a Cahill header soon after while Manager Uwe Rösler brought on Harry Forrester as Brentford chased the game.
Forrester immediately started to get at the home side but Chelsea were able to let Brentford come at them and try to exploit the space left.
And they did that to good effect with two goals in four minutes that killed the game.
The first came when Brentford lost possession in midfield and Ivanovic escaped on the right, his cut back was flicked home by Oscar although both Moore and Dean could have stopped it.
Lampard got the third when Mata turned away on the left and cross for the midfield man to volley home from six yards out.
Donaldson headed a Forrester corner wide for The Bees but the game was up by then and Brentford’s aim was to give almost 6,000 fans behind the goal something to cheer.
Instead, Chelsea scored a fourth – a corner was worked to Oscar and his deep cross was headed in at the far post by John Terry.
The Bees ended the game with ten as Jake Reeves had to go off with a head injury after Luiz cynically shoulder barged him in the face.
But Brentford’s ten had more of the ball in the final five minutes than their hosts but the game was up by then.
Both teams could have scored late goals, a Douglas effort was blocked and the Brentford captain then denied Ivanovic at the other end.
Mr Swarbrick blew up seconds later and Chelsea booked their spot in the last 16.
Chelsea: Cech; Ivanovic, Cahill, Terry, Cole; Luiz, Lampard (sub Bertrand 81 mins); Moses (sub Hazard 65 mins), Mata (sub Benayoun 76 mins), Oscar; Ba
Subs (not used): Turnbull, Azpilicueta, Ramires, Torres
Bookings: Ivanovic (69 mins), Luiz (85 mins)
Brentford: Moore; Logan, Dean, Craig, Bidwell; Forshaw (sub Saunders 78 mins), Adeyemi, Diagouraga (sub Reeves 72 mins), Douglas, Donaldson; Trotta (sub Forrester 55 mins)
Subs (not used): Lee, Hodson, Barron, Hayes
Attendance: 40,961 (Away 5907)
By Chris Wickham