NEW YORK (AP) — Naomi Osaka eliminated Coco Gauff 6-3, 6-2 at the U.S. Open with a far more confident and consistent brand of tennis Monday to reach her first Grand Slam quarterfinal in more than 4 1/2 years.

The No. 23-seeded Osaka was better throughout than No. 3 Gauff, whose repeated mistakes really made the difference in Arthur Ashe Stadium.

Osaka is a 27-year-old who was born in Japan and moved to the U.S. with her family at age 3. She has won four major championships, all on hard courts. That includes titles at the U.S. Open in 2018 and 2020.

Gauff, a 21-year-old from Florida, owns two Slam trophies. The first came at Flushing Meadows in 2023 and the second at the French Open this June.

But Gauff came out jittery at the start. Her serve was fine; other strokes were the problem. She finished with 33 unforced errors — way more than Osaka’s 12.

Trying to rework her serve during this tournament with the help of biomechanics expert Gavin MacMillan, Gauff got broken right off the bat and was down 2-0 after just five minutes, dropping eight of the initial nine points while making five unforced errors.

Whether because it’s what the prematch strategy dictated or because of how the beginning unfolded, Gauff cranked up the velocity in her second service game. The results were unimpeachable. She hit four first serves in — each arriving no slower than 110 mph, with a high of 115 mph — and held at love with a pair of aces and a pair of service winners.

Still, this is where the key difference was: Osaka used her big forehand, her best stroke, to go after Gauff’s forehand, her worst stroke, and it worked wonders. By the end of the first set, Gauff had made 16 unforced errors and Osaka only five.

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Osaka slapped her left thigh between points and repeatedly told herself, “Come on! Come on!”

That positive body language was quite a contrast to Gauff’s.