Kerber's loss to Osaka also means she will slip out of the world's top 10.
It was a disastrous start for the German, who struggled on her serve throughout. After breaking again for a 4-1 lead the wind had left Kerber's sails. The 2017 U.S. Open will be without Serena Williams, who remains sidelined due to her pregnancy, and several top men's players-Andy Murray, Novak Djokovic, Stan Wawrinka, Kei Nishikori and Milos Raonic-are skipping the event due to injury. "So that helped me focus and concentrate, which I needed as Angelique gets everything back".
Fortunately for both runner-up and current No1 Karolina Pliskova and defending champion Angelique Kerber, who became No1 right here a year ago, the biggest tennis stadium in the world now has a roof. I know that I will not give up like this. But even her biggest admirers may not have expected such a decisive victory, 6-2, 6-1-all done and dusted in an hour and 19 minutes, just as the rain began to disrupt the other matches around Flushing.
As for Osaka, she notched the biggest win of her career on Tuesday, playing clean tennis which resulted in 22 winners to 17 unforced errors and breaking on four of her six chances while saving all four break points she faced.
"I felt a little bit nervous walking on this court, especially after past year and the memories I have here", said Pliskova, whose progression to the second round was only briefly halted by the roof on Arthur Ashe stadium being closed.
Johnson, Fowler part of logjam at NY playoff event
Asked about the NY fans' reaction to him, Dustin Johnson said, "I love playing in NY ". One problem: Mitchell was misinformed, as he only needed a four to make the cut.
She next faces either Swedish qualifier Rebecca Peterson or Czech Denisa Allertova, with a potential fourth-round clash against French Open champion Jelena Ostapenko looming. Linette worked 10 break points but could only convert one of them.
Day 1 of the U.S. Open is headlined by a first-round match between No. 2-seed Simona Halep and wildcard Maria Sharapova, who is playing in her first major tournament since returning from a 15-month doping ban in April.
The game could be better.
The Czech didn't have to be anywhere near her best to see off Poland's Magda Linette and she only served at 56% throughout.
The rain washed out the majority of the action on Tuesday but before the bad weather started, 23rd seed Barbora Strycova, Yanina Wickmayer and Sorana Cirstea advanced.