Barnet came away from Ninian Park with the scalp of Championship pace-setters Cardiff in the Carling Cup first round.
Cardiff's Nick McCoy is challenged by Barry Cogan
Tresor Kandol was the hero for the League Two side, hitting a goal in each half to down a weakened Bluebirds side.
The first was handed to the Bees striker by Cardiff goalkeeper Mark Howard, whose poor clearance was returned with interest by Kandol.
Then on 54 minutes slack defending allowed Kandol to rise unmarked and power a header home from six yards out.
Cardiff: Howard, Gunter, Johnson, Weston (Blake 45), Jacobson, Flood, Cooper (Ledley 66), McKoy, Kamara (Parry 66), Campbell, Glombard.
Subs Not Used: Chopra, Corcoran.
Booked: Flood, Blake.
Barnet: Flitney, Devera, Warhurst, Charles, Gross, Cogan, Sinclair, Bailey, Puncheon (Nicolau 77), Vieira (Norville 65), Kandol (Hatch 90).
Subs Not Used: Harrison, Graham.
Booked: Puncheon, Cogan.
Goals: Kandol 32, 54.
Ref: A Penn (W Midlands).