Bourdy's stunning finish seals Wales Open win
Bourdy birdied the 16th, 17th and 18th at Celtic Manor to deny Peter Uihlein his second win of the season, the American finishing two behind due to a bogey on the last as he tried to find the birdie needed to force a play-off.
Uihlein began the day three shots clear of Bourdy and compatriot Thomas Levet but had fallen two behind after playing his first 10 holes in two over par.
The 24-year-old, who celebrated his birthday on Thursday, regained the upper hand when Bourdy bogeyed the 13th and 14th, a birdie on the 15th taking him back into the lead.
However, Bourdy then holed a curling 40ft birdie putt on the 16th and another from 12ft on the 17th to reclaim the lead, only for Uihlein to respond with a lengthy birdie putt of his own on the 17th.
Another birdie looked unlikely on the par-five 18th when Bourdy's approach came up 30ft short of the hole, but the 31-year-old promptly holed that putt as well to complete a superb 67 and finish eight under par.
Watching from the fairway behind, Uihlein knew he now needed to match that birdie to force a play-off but charged his putt six feet past the hole and missed the return.
He still finished in outright second on six under, with Denmark's Soren Kjeldsen a shot further back after a closing 66 marred only by a bogey on the 18th.
Ireland's Damian McGrane finished in a tie for sixth on two under with Ryder Cup captain Paul McGinley a shot further back.