DOHA, Qatar (AP) — Top-seeded Dominic Thiem came through with a 7-5, 6-4 win against tenacious Greek qualifier Stefanos Tsitsipas to reach the semifinals of the Qatar Open on Thursday.
The fifth-ranked Thiem, the only seeded player still in the quarterfinals, was tested by the 91st-ranked Tsitsipas, who had upset fifth-seeded Richard Gasquet in the second round.
Thiem served for the first set in the 10th game but was broken at 15-40 to even the score at 5-5. The Austrian then had to save three break points in the 12th game before taking the set.
Thiem hit two forehand winners from 15-30 to break Tsitsipas' serve in the ninth game of the second set and saved a break point in the 10th before securing his place in the semifinals.
"It's pretty slow conditions here," Thiem said. "It's pretty cold. So a break of serve is nothing really unusual. To me it happened when I had to close out the (first) set.
"Also, in the second set, I had troubles to close out the match. But it has nothing to do with the score. I think he was returning quite well."
Thiem will next face wildcard entrant Gael Monfils after the Frenchman ousted Peter Gojowczyk of Germany 6-3, 7-6 (6). Thiem has beaten Monfils all three times they've played.
Monfils is playing his first event since retiring in a U.S. Open third-round match in September with a right knee injury.
Earlier, Andrey Rublev of Russia posted a 6-3, 7-5 win over Borna Coric of Croatia in a battle between two of the ATP Tour's most promising young players.
The 20-year-old Rublev took a decisive 4-1 lead in the first set, but the tables were turned in the second set when the 21-year-old Coric went 4-2 ahead. Rublev fought back to reach 5-5, before going on to secure a place in the semifinals against Guido Pella of Argentina.
Pella ousted Bosnian qualifier Mirza Basic 6-2, 6-3 in the first quarterfinal of the day.