Defending champion Alexander Bublik stayed on course for back-to-back Generali Open Kitzbühel titles after defeating Slovakia's Alex Molcan 6-3, 6-2 to reach the semi-finals on Thursday.
The top seed looked in complete control for much of the match before producing one of the tournament's most unusual moments. Holding a set and a break advantage, Bublik served five double faults in a single game to hand Molcan a break back.
The lapse proved only a brief distraction, however, as the Kazakh quickly regained control to seal victory and continue his title defence.
"You can serve five double faults, you can still win the match," Bublik joked after the match.
The victory also made him the first defending champion to reach the Kitzbühel semi-finals since Robin Haase achieved the feat in 2013.
Standing between Bublik and another final is Argentina's Tomas Martin Etcheverry, who eased past Peru's Ignacio Buse 6-2, 7-5.
Etcheverry has established himself as one of the ATP Tour's most reliable clay-court players, with all 10 of his career ATP semi-final appearances coming on the surface. Earlier this season, he captured his maiden ATP Tour title in Rio de Janeiro.
Bublik expects another stern test.
"This year he won his first ATP title on clay. This is going to be a very challenging match, but I'll try to be ready and serve well," he said.
The other semi-final will feature Germany's Yannick Hanfmann against France's Quentin Halys.
Hanfmann produced one of the performances of the day, cruising past 2023 champion Sebastian Baez 6-3, 6-1 to reach the Kitzbühel semi-finals for the fourth time.
The 34-year-old also became the oldest semi-finalist in the tournament's history, continuing his impressive record at the Austrian clay-court event.
Halys completed the last four line-up after defeating Argentina's Mariano Navone 7-5, 6-3.
The Frenchman claimed his 17th ATP Tour-level win of the season, already a personal best, and is projected to climb to world No. 72 in the live rankings after another strong week.
With the defending champion still standing, an in-form clay specialist waiting in the wings and two experienced campaigners battling in the other half of the draw, the stage is set for an intriguing finish to this year's Generali Open Kitzbühel.
