Brentford will head to Stamford Bridge for an FA Cup with Budweiser Fourth Round Replay after a 2-2 draw with Chelsea at Griffin Park.
The Bees went ahead twice, through Marcello Trotta and Harry Forrester, and were in front inside the final ten minutes.
But The Blues, current FA Cup and UEFA Champions League holders, found a way to level late on and earn a second crack at the npower League One side.
Chelsea started brightly and both Ashley Cole and Marko Marin whistled shots across the face of goal early on.
But soon the visitors looked inferior to a bustling Brentford, particularly in the first half.
The Bees were quicker in midfield, adapted better to a sticky pitch and simply seemed more inventive than their illustrious Premier League opponents.
Trotta had Brentford’s first sight of goal, shooting over from the angle and Forrester lashed a free kick, awarded after a nervous-looking Ross Turnbull had to dive full stretch to prevent a John Terry back pass going past him, over the bar.
Forrester shot wide after tricking his way past Branislav Ivanovic and Adam Forshaw missed the target from the edge of the penalty area after great work on the left by Shaleum Logan.
Forrester then shot wide after bursting on to a Trotta lay off before a low Forshaw shot was saved.
The goal Brentford had been threatening, and fully merited, came two minutes before half time.
Forshaw won the ball off Frank Lampard 20 yards from the Chelsea goal and Forrester fired in a shot that Turnbull got down to but couldn’t hold, Trotta reacted quickest to smash home and sent the majority of a 12,000+ crowd inside Griffin Park in to delirium.
The Bees also had a penalty appeal waved by referee Jonathan Moss away late in the first period when Forrester was bundled over but they went in to break with a deserved lead.
Chelsea started the second 45 brightly and the half time introduction of Juan Mata made a difference.
Lampard had a shot blocked and Ramires shot wide while Brentford went close through Logan.
Lampard had another free kick blocked and an Oscar effort was diverted away from goal by Ivanovic but Chelsea levelled ten minutes in to the second half.
The ball dropped on the edge of the penalty area and Oscar, in the blink of an eye, took it away from two Brentford defenders and toe-poked it in to the top corner.
It was an outstanding goal and Chelsea flourished, Moore saved from Mata and a Lampard header was blocked before Oscar shot wide.
But Brentford soon found their poise again and took the game to their visitors.
Lee Hodson had a shot blocked and a vicious Forshaw volley was diverted away before Brentford went ahead with 17 minutes left.
Substitute Tom Adeyemi raced on to a Clayton Donaldson pass and was brought down by Turnbull when through on goal.
Mr Moss pointed to the spot but decided not to send Turnbull off when he certainly could have.
Forrester took the responsibility and slotted the penalty in to Turnbull’s right hand corner.
Chelsea had 17 minutes to save the tie and Brentford fought to preserve their lead.
Gary Cahill missed the target with a header and Mata fired across the face of goal before Moore saved an Ivanovic overhead.
Fernando Torres, who had been peripheral to that point, shot wide and an Oscar effort was blocked before Donaldson missed the target at the other end.
But Torres showed why Chelsea spent £50m on him when he curled in an equaliser from the edge of the penalty area with seven minutes left.
Moore had to save twice from Lampard as Chelsea sought to end it at Griffin Park and a Ramires shot was blocked before Donaldson volleyed over from a tight angle.
The visitors had loud penalty appeals when a Mata shot appeared to hit Dean on the arm but Mr Moss refused to point to the spot and brought the game to an end moments later to send the teams to a different part of West London for another go.
Brentford: Moore; Hodson, Dean, Craig, Logan; Forshaw (sub Saunders 84 mins), Douglas, Diagouraga; Donaldson, Trotta (sub Adeyemi 70 mins), Forrester (sub Barron 79 mins)
Subs (not used): Lee, Reeves, Dallas, Hayes
Chelsea: Turnbull; Ivanovic (sub Azpilicueta 79 mins), Cahill, Terry, Cole; Lampard, Ramires; Marin (Mata h/t), Oscar, Bertrand (sub Ba 82 mins); Torres
Subs (not used): Hilario, Ferreira, Benayoun, Ake
Bookings: Cahill (44 mins), Turnbull (72 mins)
Attendance: 12,146 (1,830 away fans)
By Chris Wickham