(Reuters) -Top seed and home favourite Alexander Zverev beat Brandon Nakashima 7-5 6-4 to advance to the semi-finals of the Stuttgart Open on Friday while Americans Taylor Fritz and Ben Shelton also reached the last four.
Zverev is seeking his first grasscourt title and he was involved in a tight opening set which was tied at 5-5 when the German switched gears in the final two games to clinch it.
But Zverev was far more dominant against his American opponent in the second set as he finished the match with 31 winners in a contest that lasted 90 minutes.
"I'm in the semi-finals now and now I really want to focus on trying to do the best I can," Zverev said.
"I know the opponents are going to get tougher but I'm really happy on the court right now I'm really happy in Stuttgart and I'm looking forward to the next two days."
Zverev will play third seed Shelton next after the American, who was virtually unstoppable on his first serve, beat Jiri Lehecka 6-4 6-4, firing 18 aces.
Shelton was so dominant in the second set that he did not lose a single point on serve while he won 100% of his first-serve points in the match, with victory ensuring he will break into the top 10 for the first time in his career.
Marton Fucsovics had beaten Fritz in straight sets in Stuttgart two years ago but this time the American, who has yet to drop a set at the tournament, came out on top in a dominant 6-3 6-4 victory.
Although Fritz was involved in some long baseline rallies, he relied on his serve, sending 12 aces past the Hungarian to set up a semi-final clash with Felix Auger-Aliassime, who beat the 17-year-old German Justin Engel 7-6(3) 6-3.
Engel had claimed his first professional victory on grass earlier this week when he beat James Duckworth, following it up with an upset win over seventh seed Alex Michelsen, but beating Auger-Aliassime proved to be a step too far for the teenager.
"His serve was so incredibly good today that I felt pressure in my own service games," Engel said.
"But it was great fun playing in front of this crowd again. I can't wait to play here again next year."
(Reporting by Rohith Nair in BengaluruEditing by Toby Davis)
