Djokovic will face fifth-seeded Stan Wawrinka, who beat him for the French Open title.
Wimbledon champion Djokovic, aiming for a historic career grand slam of all nine ATP 1000 Masters titles, had to contend not only with being broken but also some trick shots from France’s Benoit Paire, who ultimately succumbed to a 7-5 6-2 defeat.
Although Knapp briefly harnessed her serve and led 40-love, Williams rallied for a break that ended the first set in just 23 minutes.
Williams won the tournament for the first time on her sixth try past year, beating Ivanovic in the finals.
Bencic will meet with her team before deciding whether she can play in the Connecticut Open next week, the final tournament before August 31-Sept. “Like, literally thinking about all this stuff that, you know, the women are doing in sports”, she said.
The tournament’s defending champion won 54 points to Knapp’s 25 and otherwise dominated Thursday’s 54-minute match at the Lindner Family Tennis Center in Mason.
Holding his serve, he then broke his opponent before holding again to seal progression into the last eight with a 4-6 7-6 (7-3) 7-5 scoreline.
The scoreboard reflected service games with Wawrinka’s power from the base-line and Djokovic’s athleticism up-and-down the court getting the job done in equal measure.
Caroline Garcia beat fourth seed Petra Kvitova 7-5, 4-6, 6-2 after another night rainstorm which pushed finishing time of some matches to after midnight.
Bencic later said she did not feel the injury was too serious, but former world number one Azarenka’s fitness is more of a concern – the Belarusian quitting midway through her clash with Anastasia Pavlyuchenkova due to a right thigh injury.
“I think not just me, but a lot of people in America and outside America, are frustrated and concerned and really scared”, Williams said.
Wozniacki had her chances in the second set but frittered away 10 of 11 break points, while the Belarussian converted two of her four chances.
He will play Alexandr Dolgopolov, the qualifier who made short work of Tomas Berdych on Friday evening, winning 6-4 6-2 in just over an hour. She quit three games into the second set. “I had to unfortunately make that decision. Obviously I felt like I had that match in control”. “This guy, even when he’s not playing his best, he can beat me the way he did today”.