De Bruyn, a 24-year-old German ranked No. 818, shot a nine-under 64 to open up a surprise four-shot lead.

Trailing in his wake was Australia's David Micheluzzi, 10 shots adrift of the leader in a share of 64th place. Jason Scrivener was a further shot back after carding a 75, while late starter Haydn Barron was four-over in the closing stages.

De Bruyn, who graduated from qualifying school at the end of 2023, made 11 birdies at Green Eagle Golf Courses in Hamburg, including six of his first seven holes and then each of his final four holes.

He had missed the cut in six of his last eight tournaments, with the undoubted highlight in that period being a tie for 13th at the Indian Open.

Laurie Canter of England and Jack Davidson of Wales, who is ranked No. 810, were tied for second place after shooting 68s in a rare par-73 layout on the DP World Tour.