Third-ranked defending champion Alexander Zverev took bragging rights in his sibling rivalry, beating 15th-seeded older brother Mischa 6-3, 7-5 on Thursday to reach the ATP Washington Open quarter-finals.
It was the first ATP meeting for the German siblings, 21-year-old top seed Alex besting 30-year-old Mischa as he rarely did in boyhood battles.
"We had a great time," Alex said. "I was happy and enjoying the moment. We played near our best. It was unbelievable.
"I just hope it happens again and I hope it happens at later stages of bigger tournaments. I hope we meet again someday in a final."
Mischa was nearly in tears at the start at a family dream come true.
"When we came back to the benches I had to fight back my tears," he said. "It was a big day, big match. It was very emotional for me. It was just a great day."
Next up for Alex will be Japanese seventh seed Kei Nishikori, who dispatched Canadian ninth seed Denis Shapovalov 7-6 (7/1), 6-3.
"There will be a lot of points from the baseline," Nishikori said. "I've got to work the point and play more aggressively and move the ball around."
Three-time Grand Slam champion Andy Murray of Britain, in his first hardcourt event after an 11-month layoff with a right hip injury, was set to play the last match against Romanian Marius Copil.
The rain-hit US Open tuneup event also saw US second seed John Isner ousted by 152nd-ranked compatriot Noah Rubin 6-4, 7-6 (8/6) and Japanese third seed Naomi Osaka, nagged by a right leg injury, lost to Poland's Magda Linette 6-2, 3-6, 6-3 in the companion WTA event.
"It definitely bothers me a bit out there on the court, but it isn't anything serious," Osaka said. "We're going to prep and get healthy."
Alex broke Mischa for a 5-3 lead and held again to win the all-Zverev first set in 29 minutes. Alex broke again in the penultimate game and held once more to win after one hour and 51 minutes on a forehand drop volley winner.
"I actually played better than in practice," Mischa said. "When he hits certain shots, I know what he's thinking. But that's a disadvantage, too, because he knows what I'm thinking."
The elder Zverev, smiling, walked around the net and shared a hug with Alex, patting him on the back as they parted for their chairs.
"I had a big smile. I played OK. I was able to keep up with him," said Mischa, to which Alex replied, "That comes from a person who kicks my ass every single time in practice."
Mischa won his first ATP title in June at Eastbourne, a feat he credits his brother for helping him to achieve.
"It was something I always wanted," Zverev said. "It was him being young and being overly positive that helped me be young, keep working hard and achieve my dream."
Alex noted his mother watches more of Mischa's matches, saying, "Apparently the dog has to go to the bathroom every time I play."
- Low-energy Isner ousted -
Ninth-ranked Isner, fatigued after a first-ever Grand Slam semi-final at Wimbledon and an Atlanta title run, blamed his low-energy outing on recent deep tournament runs and rain.
"Noah played with more energy. He was just tougher than I was. He was hungry out there," Isner said. "If I would have won, I don't know what I would have done."
Rubin later lost 6-3, 6-2 to Russian 16th seed Andrey Rublev, who eliminated American Tommy Paul 7-6 (7/5), 6-4.
Isner plays at Canada and Cincinnati the next two weeks in major tuneups for the US Open, which starts August 27.
"For me, this could very well be a good loss. I need a little rest. There are some big tournaments coming up. I want to be full of energy for those.
"It's unfortunate the rain has wreaked havoc so far. It tires you out. It's mentally taxing. You're sitting around hours on end."
Brothers Mischa (L) and Alexander Zverev of Germany, seen during a doubles match at a tournament in Halle, in June 2018
Noah Rubin of the US serves during the BB&T Atlanta Open tournament in Georgia, on July 26, 2018