Latvia's Ernests Gulbis stunned top-seeded American John Isner 1-6, 6-3, 6-3 on Saturday to reach the final of the Intrum Stockholm Open in Sweden.
"I was fighting for every point," said Gulbis, who will try for his sixth title and first since 2014. "I think I returned a lot smarter in the second and third set."
Isner, 33, was coming off two marathon matches in which all six sets went to tiebreakers.
Gulbis will face Greek No. 3 seed Stefanos Tsitsipas in the final. Tsitsipas cruised past second-seeded Fabio Fognini of Italy 6-3, 6-2 in the other semifinal.
"Fabio was going for shots and the beginning of the match was really tough," said Tsitsipas afterward. "I was patient in the rallies. That is how I got the win today."
It's the third final of the year for Tsitsipas, 20, who is searching for his first career title.
VTB Kremlin Cup
No. 3 seed Karen Khachanov outlasted No. 2 seed Daniil Medvedev 6-1, 6-7 (5), 6-3 to win an all-Russian semifinal in Moscow.
Medvedev had beaten his good friend Khachanov -- both are 22 years old -- in their only other meeting.
Khachanov will take on unseeded Adrian Mannarino in the final after the Frenchman toppled Italian Andreas Seppi 7-5, 7-5 in the other semifinal.
Mannarino, in his sixth final, is still seeking his first championship, while Khachanov is trying for the third of his career and second this season.
Khachanov has won both of their previous meetings.
European Open
Frenchman Gael Monfils upset second-seeded Argentine Diego Schwartzman 6-3, 6-4 to reach the final at Antwerp, Belgium.
Monfils is trying to become the third straight French winner in the event.
"I am relieved to have been able to win this match in two sets," said Monfils afterward. "Luckily I could count on my strong first service."
He'll first have to get past top-seeded Kyle Edmund of Great Britain, who beat No. 4 seed Richard Gasquet 6-3, 6-4 to scuttle the opportunity for an all-French final.
Edmund is still seeking his maiden ATP title, while Monfils is chasing his eighth and second of 2018.
Monfils, 32, beat Edmund, 23, at Wimbledon in 2017 in their only previous meeting.
--Field Level Media