WASHINGTON: Ilya Ivashka used an impressive performance on serve to topple top-seeded Pablo CarrenoBusta 7-6 (7/2), 6-3 on Thursday and reach the semi-finals of the ATP hardcourt tournament in Winston-Salem, North Carolina.Ivashka, a 27-year-old from Belarus ranked 63rd in the world, notched his third straight win over a seeded player to book a semi-final clash with 22-year-old Finn Emil Ruusuvuori, who ousted 14th-seeded Richard Gasquet of France, 7-6 (7/5), 6-1.”Of course it’s a great feeling,” said Ivashka, who reached the final in Munich in May. “I had a great match today. These conditions suit me.”Ivashka, who said the pressure was all on 12th-ranked CarrenoBusta as the top seed, lost just nine points on serve and didn’t face a break point.”I think I was playing very aggressive and I was not giving a lot of time to him, trying to push him from the return from the baseline,” Ivashka said. “I was trying to go to the net to play as aggressively as I could and it worked.”Gasquet served for the first set against Ruusuvuori at 5-4 but was broken, and once the Finn wrapped up the set in a tiebreaker he was on his way.He closed out the match in 93 minutes with his fourth break of serve as Gasquet struggled late in the steamy conditions.In other quarter-final action, Carlos Alcaraz— the 18-year-old Spaniard ranked 54th in the world — beat American Marcos Giron 7-6 (7/2), 6-2 to book a semi-final showdown with Sweden’s Mikael Ymer.Ymer, ranked 90th in the world, upset 13th-seeded American Frances Tiafoe 6-7 (2/7), 6-2, 6-3.