Brentford were bundled out of the Cup at the hands of Blue Square Premier leaders Wrexham thanks to a stunning strike from James Tolley.
The Wrexham striker smashed a rising half volley into the top corner from 25 yards just after the half hour to deservedly send the Welshmen into the third round draw.
Brentford's best chance came when Sam Saunders' curling free-kick was tipped wide by goalkeeper Joslain Mayebi in the 17th minute, but the home side offered little after that.
Gary Alexander saw a diving header saved on the goalline, but it was always the non-league outfit who looked the more dangerous against a shaky Bees defence.
Midfielder Adrian Cieslewicz's pace was a constant threat to the home side and he, Jake Speight and Curtis Obeng all went close for the visitors in a one-sided first half.
Brentford reacted after the break, but always looked toothless in front of goal as Wrexham defended with their lives to clinch a deserved win.
Defender Leon Legge might have earned his side a replay deep in injury time, but powered his header just over the crossbar.