Top seeds John Isner moved into the Atlanta semifinals, but he was overshadowed by an unsporting Nick Kyrgios, who appeared bored throughout his match and retired down a break in the second set.
Kyrgios struggled with a hip problem and saw the trainer midway through the first set, then put little effort into the final four games before pulling the plug midway through the changeover with Norrie leading 7-5, 3-0. The No. 2 seed was booed heavily after making his decision and received more boos as he trodded off court.
Up 40-0 at 4-5, Kyrgios flung up a flat-footed serve facing forward, then offered several other weak efforts. On set point down on his serve, the Australian deposited a poor, stationary drop shot into the net, handing Norrie the edge. Kyrgios then double faulted on break point at 0-1 in the second.
Norrie was sympathetic in his on-court interview, expressing concern for Kyrgios’ injury.
Hours earlier, Isner had needed three sets to defeat Mischa Zverev 7-5, 4-6, 6-1. Isner smashed a characteristic 21 aces while facing just one break point, rebounding from the second set disappointment to win the first five games of the final frame. The American won 38 of 40 points on his first serve, including all 11 in the decisive final set.
He made his first decisive move at 0-1 in the third set, forcing the onrushing Zverev to hit an awkward half-volley off a soft forehand return. The German could do nothing with the ball, handing the top seed his virtual ticket to the semifinals. Isner then broke again with a straightforward pass to cement his lead.
Zverev capitalized on his only break point when Isner double faulted at 2-3 in the second set, and the veteran German served out the frame to level the match. Isner, for his part, had smashed a handcuffing forehand on his third set point of the first set to go in front.
Zverev had 11 aces of his own, but he was no match for the four-time Atlanta champion.
“I just keep staying positive. I told myself, even though I did get broken in the second set I was going to be very very tough to break,” Isner said. “I’ve been playing well. I played very well today.”
Elsewhere, No. 8 seed Ryan Harrison pushed past third seed Hyeon Chung — and sporadic emotional outbursts — in a 6-7, 6-2, 7-6 win spanning nearly two and a half hours. Harrison will meet Norrie in the semifinals. Matthew Ebden, the No. 4 seed, breezed past Marcos Baghdatis 6-3, 6-2, to set up a meeting with Isner.
