Christian Moore was the Telford United hero as the Nationwide Conference side dumped Brentford out of the FA Cup at an excited New Bucks Head.
The record signing, who moved from Burton Albion six weeks ago for a fee of around £20,000, grabbed a hat-trick to inspire the shock victory.
Brentford started the brighter and Matt Somner went close with two headers as the Bees forced a flurry of five early corners.
But Telford soon began to get on top and Michael Blackwood missed an excellent chance to give his side the lead when he hesitated when clear through on goal and allowed Ibrahim Sonko to clear.
But the Bucks did take the lead on 26 minutes when Brentford keeper Paul Smith failed to clear a high cross from Matthew Clarke and Moore was on hand to rifle a shot into the roof of the net from a tight angle at the back post.
Lee Mills had a half-chance to double the lead just before half-time but could only manage a weak left-foot shot from the edge of the box after good work from Blackwood.
The Bucks started the second period brightly and Moore was only denied a second goal by a brilliant last-ditch tackle by Sonko after Mills and Fitzroy Simpson had contrived to send him clear.
Brentford had been poor in the first half but thought they had got back on level terms in the 52nd minute when Jay Tabb fired home from ten yards after Ben May had headed down Michael Dobson's cross, but the effort was ruled out for offside.
And that proved crucial as just six minutes later, the tie tipped in Telford's favour.
A long clearance from goalkeeper Chris MacKenzie sent Moore clear and he was adjudged to have been pushed in the back by Sonko.
The tall defender, who had already been booked in the first half, was given a second yellow card and dismissed and Moore, who saw his penalty brilliantly saved by Smith, reacted first and hammered home the rebound.
Brentford pushed men forward in a desperate bid to pull a goal back and should have done when substitute Stephen Evans headed Mark Peters' cross over the top when unmarked from just eight yards.
But it was Telford's day and after Matt Clarke and Mills had both gone close, Moore completed his hat-trick and secured the victory by hammering home a penalty after Evans had been adjudged to have handled the ball.