Novak Djokovic and Alexander Zverev continued on their semifinal collision course Saturday at the US Open.
Djokovic moved to the day session in his match against Kei Nishikori. The Japanese star had stunned Djokovic back at the 2014 US Open, but since had lost 16 straight.
Today, Nishikori got an early break to send a message to Djokovic. Djokovic would recover but errors cost him the breaker. And Djokovic got control and while he still wasn’t at his best, he got the win.
“It was a tough battle,” Djokovic said. “So far the toughest match of the tournament for me. The opening two rounds obviously felt well, played good. But the pace of the ball and the speed of Nishikori’s tennis today was just higher than the opening two rounds’ opponents that I had.
“I thought he played great. He didn’t give me much time. He wanted to make me uncomfortable and defensive, and he managed to do that I felt like for maybe a set, set and a half.
“Once I adapted to the pace of his ball, I felt better on the court. I felt like I’m starting to gain the momentum and control of the match. Served well when I needed to. When I was up, I just kept pushing and kept applying pressure on his service games.”
In the evening, Zverev got a retirement from Jack Sock who was down 3-6, 6-2, 6-3, 2-1 when the groin that flared up after the first set prohibited him from continuing.
While Sock went down, Americans did come up big.
Jenson Brooksby played his first five set match and came away with a win over Australian Open semifinalist Aslan Karatsev 6-2, 3-6, 2-6, 6-3, 6-3.
“I’m proud of battling my adversity, whether it’s my own head or what’s going on out there on the court,” the 20-year-old Brooksby said. “I mean, today was a battle obviously. I don’t know how long it was, but I thought I started out solid. Good first set. Still a couple things I could have done better.
“The break in the second. I just lost the mental energy way too much in the second set and third set. That’s not really easy to come back from, but I just told myself to keep staying in the present moment, keep breathing, keep staying positive, focus on what I’m working on out there.”
Broosksby will now face Djokovic on Monday in the fourth round.
“It will be a great challenge,” Brooksby said. “One of the toughest there can be. But I’m really believing in myself with what I’m showing out there so far. I got a great team around me to help me recover tomorrow. Yeah, I go out there to battle again on I’m sure Ashe probably, I would assume.
“That will be really exciting. I’m sure it will be a full crowd. I’m excited to see how well I can focus, see how well I can play with one of the biggest challenges and with one of the biggest crowds in a court that you can get.”
Big man Reilly Opelka cruised into the fourth round with a straight set win over Nikolaz Basilishvili in three sets.
Italian men went 2-1. Andreas Seppi fell to qualifier Oscar Otte while Matteo Berrettini and Jannik Sinner both won five setters.
And Denis Shapovalov was upset in straight sets by Lloyd Harris 6-4, 6-4, 6-4.
Tomorrow, the kids are back. Teen Carlos Alcaraz, Frances Tiafoe, Felix Auger Aliassime all bid for a first US Open quarterfinal.
Daniil Medvedev hopes to move on against Dan Evans.
SUNDAY US OPEN SCHEDULE
Arthur Ashe Stadium, Day Session – 12:00 PM Start
Elina Svitolina (UKR)  vs. Simona Halep (ROU) 
Daniel Evans (GBR)  vs. Daniil Medvedev (RUS) 
Arthur Ashe Stadium, Night Session – 7:00 PM Start
Frances Tiafoe (USA) vs. Felix Auger-Aliassime (CAN) 
Barbora Krejcikova (CZE)  vs. Garbine Muguruza (ESP) 
Louis Armstrong Stadium, Day Session – 11:00 AM Start
Botic Van de Zandschulp (NED) (Q) vs. Diego Schwartzman (ARG) 
2. Women’s Singles – 4th Round – Not Before 1:00 PM
Angelique Kerber (GER)  vs. Leylah Fernandez (CAN)
Elise Mertens (BEL)  vs. Aryna Sabalenka (BLR) 
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