Nicolai Hojgaard birdied the final hole to claim a one-shot victory at the Italian Open on Sunday, just a week after his twin brother Rasmus won the European Masters in Switzerland.
The 20-year-old Danes are the first siblings to win titles in back-to-back events in European Tour history.
Nicolai Hojgaard carded a level-par final round of 71 to finish on 13-under for the tournament, one stroke clear of Poland's Adrian Meronk and European Ryder Cup star Tommy Fleetwood.
He holed a short birdie putt on the par-five 18th to avoid the need for a play-off, with brother Rasmus watching on.
"It's crazy," he said. "It's been such a tough day.
"I've been through every emotion in my body and brain, so to finish it off with an up-and-down is perfect.
"It's what I've been working hard on all year and all my life so I'm really pleased with it."
Nicolai will enjoy a rise from his current world ranking of 394th into the top 200 after his maiden European Tour success.
Rasmus' triumph in Crans-Montana last Sunday was his third of his young tour career.
The pressure appeared to be getting to Nicolai Hojgaard on the back nine at Marco Simone Golf Club in Rome, the venue for the 2023 Ryder Cup.
He made two bogeys to drop into a tie for the lead with Meronk, whose 67 catapulted him into contention.
Fleetwood also struggled for his best form but joined the duo at the top with a closing birdie.
Hojgaard held his nerve, though, edging over the line to leave Englishman Fleetwood still without a win since November 2019.
Leading final-round scores from the European Tour's Italian Open at Marco Simone Golf Club in Rome on Sunday (par 71/GBR & IRL unless stated):
271 - Nicolai Hojgaard (DEN) 66-69-65-71
272 - Adrian Meronk (POL) 70-69-67-66, Tommy Fleetwood 66-68-67-71
273 - Francesco Laporta (ITA) 66-70-69-68
274 - Masahiro Kawamura (JPN) 67-70-71-66, Richard Bland 70-69-68-67, Edoardo Molinari (ITA) 65-70-70-69
275 - Pablo Larrazabal (ESP) 70-70-70-65, Scott Jamieson 70-67-71-67, Johannes Veerman (USA) 67-67-72-69, Mikko Korhonen (FIN) 68-66-68-73
276 - Shubhankar Sharma (IND) 75-66-69-66, Adri Arnaus (ESP) 66-68-72-70, Min Woo Lee (AUS) 64-68-71-73