STUTTGART, Germany — German qualifier Dustin Brown upset top-seeded Alexander Zverev 6-4, 6-7 (3), 6-3 Thursday to reach the quarterfinals of the Stuttgart Open.
Brown was playing just his second tour-level match of the year but hit a number of spectacular winners to beat the fifth-ranked Zverev and record his first win against a top-10 opponent since 2017.
The 170th-ranked Brown, who is best known for beating Rafael Nadal at Wimbledon in 2015, next plays Gilles Simon or Felix Auger-Aliassime at the grass-court tournament.
Matteo Berrettini caused another upset earlier Thursday, defeating second-seeded Karen Khachanov 6-4, 6-2.
The Italian next faces American player Denis Kudla, who advanced with a 7-5, 6-7 (3), 7-6 (3) win over Gael Monfils.
The Stuttgart Open made the switch from clay to grass in 2015.
DALLAS – Marcos Giron advanced to the second round of the Dallas Open with a 6-4, 6-7 (1), 6-1 victory over Alex Rybakov on Tuesday.
The seventh-seeded Giron, who reached the semifinals of the inaugural event a year ago, responded quickly after failing to close out the second set, winning the first five games of the deciding set.
Rybakov broke his fellow American when Giron was serving for the match in the second set. Then Rybakov won the first six points of the second-set tiebreaker.
“I’m really happy with how I was able to reset in the third and just get back to the game plan from the beginning and elevate,” Giron said. “He played well and served well and kind of hung in there.”
Eighth-seeded Adrian Mannarino of France won the final five points of a first-set tiebreaker and the last four games of the second to beat American Steve Johnson 7-6 (6), 6-2.
J.J. Wolf, the No. 6 seed, had little trouble in a 6-3, 6-3 victory over fellow American Brandon Holt.
John Isner, the fifth seed and unofficial tournament host in his hometown event, played later Tuesday. Like Giron, Isner lost in the semifinals last year.
DALLAS – Wild-card entry Jack Sock opened with a 7-6 (2), 4-6, 6-4 victory over Ilya Ivashka at the Dallas Open, setting up a second-round meeting with top-seeded fellow American Taylor Fritz.
Sock broke Ivashka’s serve in the final game to win the match. Ivashka fell behind 2-0 to start the final set but broke Sock to get back on serve.
Down a break early in the second set, Ivashka rallied to force the deciding set after Sock cruised in the first-set tiebreaker.
The eighth-ranked Fritz is back for the second Dallas Open after losing in the semifinals as the top seed in the inaugural edition of the indoor hard-court event last year. Defending champion Reilly Opelka isn’t in the field.