US Open 2019: Here are major headlines from Day 6

US Open at a glance - Day six

Defending champion Naomi Osaka overpowered 15-year-old Coco Gauff 6-3, 6-0 in 65 minutes to keep her title defense on track before sharing a warm embrace with an opponent overwhelmed by the occasion in the New York spotlight. 

Three-time champion Rafael Nadal cruised into the last 16 with a 6-3, 6-4, 6-2 win over 170th-ranked South Korean qualifier Chung Hyeon.

Second seed Nadal returned from three days of rest after a second-round walkover to move through to a meeting with 2014 title-winner Marin Cilic or leading US hope John Isner.

Russia's Andrey Rublev eliminated Australian 28th seed Nick Kyrgios to qualify for the US Open last 16 on Saturday with a 7-6 (7/5), 7-6 (7/5), 6-3 win.

The 43rd-ranked Rublev, who beat Roger Federer in Cincinnati this month, will play Italy's Matteo Berrettini, the 24th seed, for a spot in the quarter-finals.

Taylor Townsend is charging into the US Open spotlight the same way she charges to the net in her matches, stars and strangers congratulating her run to the last 16.

The 23-year-old American left-hander defeated Romania's 106th-ranked Sorana Cirstea 7-5, 6-2 in 87 minutes to book a fourth-round meeting with Canadian teen Bianca Andreescu for a quarter-final berth.

Canadian Bianca Andreescu brushed aside Caroline Wozniacki on to reach the last 16 in her US Open main draw debut.

Andreescu, who has already won titles at Indian Wells and Toronto during an injury-hit 2019 season, beat twice finalist Wozniacki 6-4, 6-4 to remain undefeated in completed matches since early March. 

Kristie Ahn has snuck under the radar at the US Open, the 27-year-old American wildcard of Korean heritage overshadowed by attention to Coco Gauff and Taylor Townsend.

But Ahn has enjoyed great success, taking her first two Grand Slam wins even as a 141st-ranked longshot in her quarter of the draw, which lost Simona Halep and Petra Kvitova.

After beating Svetlana Kuznetsova and Anna Kalinskaya, Ahn beat Latvia's Jelena Ostapenko, the 2017 French Open champion, on Saturday. She gets Belgian 25th seed Elise Mertens in the fourth round.

(File photo)

Rafael Nadal was wearing a purple jacket after his victory over South Korea's Chung Hyeon when an announcer remarked purple was the color of royalty and he was the King of Clay for his 12 French Open titles.

Could he be the King of New York also? "I'm not king for nowhere," Nadal said.

"I just like this color." After joking how he spent many hours selecting it, Nadal admitted he chose the colors with apparel maker Nike many months earlier and didn't even recall his selection before seeing it.