The underdogs scored three minutes before half-time, Marcello Trotta arrowing home after Turnbull parried a 25-yard curler from Harry Forrester. Ten minutes after the break, Oscar levelled for Chelsea with a lovely shot into the top-left corner.
In the 72nd minute, Turnbull sent Tom Adeyemi sprawling and Forrester, 22, swept the spot-kick into the bottom-left corner.
With home fans lighting flares in the Griffin Park stands, an unforgettable victory looked to be on the cards, until Torres swept home his late equaliser from the edge of the box to take the tie to a replay and deny his side's west London neighbours a memorable upset.
Leeds shock spurs
LEEDS: Eight-time cup winners Tottenham Hotspur were dumped out of the FA Cup in a 2-1 fourth-round loss at Championship club Leeds United on Sunday. Andre Villas-Boas’ side were unable to pull back a two-goal deficit established early in the second half by their second-tier hosts.