Nishioka served his most dominant victory so far in a week which led him to beat fourth seeded Alexandr Dolgopolov
Japan's Yoshihito Nishioka continued his remarkable run at the Atlanta Open, by stunning Horacio Zeballos 6-4, 6-4 to reach his maiden ATP Tour semi-final on Friday.
Nishioka did not drop a serve as he posted his most dominant victory so far in a week that also saw him oust fourth seeded Alexandr Dolgopolov.
The 20-year-old Nishioka advances to the semis where he will face second seeded Aussie Nick Kyrgios, who won a tight match against fifth seed Fernando Verdasco 6-4, 6-7 (7/5), 6-3.
"I`ve been working on my serve a lot. More percentage, more power," said Nishioka.
"And before I was very emotional, throwing racquets and getting frustrated. But I've been more calm since Wimbledon. I think that's why I`m winning more now."
Nishioka, who is ranked 97th in the world, opened the match by breaking Zeballos, and then maintained the lead throughout the remainder of the set. Nishioka lost just three points on serve in the opening set.
The second set was identical to the first, with Nishioka breaking the Argentine in the opening game and only dropping three points on serve to clinch the match.
Nishioka broke into the top 100 last month after winning the lower level ATP Challenger Tour event in Winnetka, Illinois. He also reached the quarter-finals of the Memphis Open five months ago.
Kyrgios broke Verdasco to jump out to a 3-0 lead in the final set. He dropped just five points on his serve in the final set to win the match. With the victory, Kyrgios reaches his first semi-final since the Estoril Open in April.