NEW YORK—Sascha Bajin serves a variety of roles as Naomi Osaka's coach.

Bajin devises drills, sets strategy and offers plenty of positive motivation, but his most important function is peace maker.

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When Osaka beats up on herself, Bajin steps in to soothe self-implosion.

"I mean, he's helped me a lot," Osaka said of Bajin. "It's mostly been with, like, myself. Like, I fight myself a lot, so he's sort of been, like, the peacemaker in between. And, yeah, I feel like he's a really positive person, and he sort of tells me not to be so hard on myself. So I'm grateful for him for that."

The 20th-seeded Osaka powered past Laura Siegemund, 6-3, 6-2, into the US Open second round. Osaka knocked off Daria Kasatkina to capture the biggest title of her career at Indian Wells in March.

Osaka, who will play Julia Glushko in round two, said master a Grand Slam title remains her primary goal.

"Regarding the Grand Slams, I think it would be really sad if I kept playing for years and my biggest goal was to get to the quarters of a slam," Osaka said. "I think everyone plays slams to win, especially the younger players now. Like Ostapenko won French Open. So I think, of course, everyone knows that there is a chance that you can win a Grand Slam. "

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