Delray Beach: Japanese qualifier Yoshihito Nishioka booked his first ATP quarter-final on Thursday with a 6-1, 6-3 win over Marinko Matosevic at Delray Beach.
Nishioka, a 19-year-old left-hander, notched just his second tour-level win, converting five of his nine break opportunities in the 69-minute encounter.
"I`m so happy," said Nishioka, ranked 154th in the world. "At the beginning I was so nervous, but I think he was nervous, too. I just tried to make every ball. Every shot, I was focused on it."
Nishioka is the first teenager to reach the Delray Beach quarter-finals since Bernard Tomic in 2012.
He`ll face Australia`s Tomic for a place in the semi-finals. Tomic, now 22, held on Thursday to beat eighth-seeded Serbian Viktor Troicki 6-3, 6-7 (2/7), 6-4.
Tomic withstood 13 aces from Troicki, who is his doubles partner this week, sealing the win in just under two hours.
"Today was very cold so it was tough for both of us," said Tomic, who reached his fourth quarter-final of the season.
"It was good tennis. We both served pretty good. I was happy to win because it`s a tough match playing Viktor."
American Donald Young continued his strong start to the season, reaching his third quarter-final of 2015 with a 6-3, 6-2 victory over Colombian Alejandro Gonzalez.
Young, ranked 56th in the world, needed just 67 minutes to book a meeting with third-seeded Ukrainian Alexandr Dolgopolov.
Dolgopolov beat American Tim Smyczek 6-2, 6-4 to reach his first quarter-final of 2015.
"The wind was maybe more than the first day, so I needed to stay concentrated," Dolgopolov said. "Sometimes I got nervous, but I think I handled it quite well."
Young is riding a wave of confidence after reaching the semi-finals last week at Memphis, where he lost to second-seeded Kevin Anderson of South Africa.
"I beat some quality players there, three in a row, which is something I haven`t done often in my career," Young said. "I got a lot of confidence from that and I came back in a couple situations, a couple tight sets, so that was good."
Friday`s other two quarter-finals had already been set.
Taiwan`s Lu Yen-Hsun upset top-seeded Anderson 7-6 (8/6), 6-3 on Wednesday and will take on French fifth seed Adrian Mannarino, while Croatian fourth seed Ivo Karlovic will play seventh-seeded American Steve Johnson for a semi-final spot.