San Francisco Frontiers - Sinner on the march as tearful Gauff, Swiatek toil at US Open

Sinner swatted Australia's Alexei Popyrin aside 6-3, 6-2, 6-2 to stretch his Grand Slam winning streak on hard courts to 23 matches.

The Italian top seed has made a convincing start in his bid to become the first man to repeat as US Open champion since Roger Federer won five in a row from 2004-2008.

"I'm very happy that I managed these matches as good as I could," said Sinner, who dropped only four games in his opening win before blasting past the 36th-ranked Popyrin.

"I am aiming to improve on the serve but the rest (of my game) I am quite comfortable with."

Sinner faces Canadian 27th seed Denis Shapovalov in the third round on Saturday.

He has reached the final of all three Grand Slams this season, winning the Australian Open and Wimbledon either side of a defeat to Carlos Alcaraz at the French Open.

Third seed Alexander Zverev cruised to a 6-4, 6-4, 6-4 win over Britain's Jacob Fearnley, while Lorenzo Musetti eased past Belgium's David Goffin.

Russian 15th seed Andrey Rublev beat American wild card Tristan Boyer in four sets. He advances to a last-32 tie with Hong Kong's Coleman Wong.

Wong, a 21-year-old qualifier, extended his New York fairytale with a 7-6 (7/5), 6-2, 4-6, 6-4 win over Australian Adam Walton.

The 173rd-ranked Wong had already made history earlier in the week by becoming the first man from Hong Kong to win a Grand Slam singles match.

"It's literally something that I've dreamed of, that I think every tennis player dreams of -- to keep going in a Slam," said Wong.

Karen Khachanov became the biggest casualty so far in the men's draw as the Russian ninth seed blew a two-set lead in his loss to Poland's Kamil Majchrzak.

- Tearful Gauff digs deep -

Gauff displayed great resolve to overcome another shaky performance that reduced her to tears in the night session on Arthur Ashe.

Third seed Gauff shrugged off Croatia's Donna Vekic 7-6 (7/5), 6-2 despite being broken four times in the opening set as her serving woes resurfaced.

"Honestly, today was a tough match for me, but I'm just happy with how I was able to manage it," said Gauff, choking back tears. "It's been a rough couple of weeks."

"I was just trying to tell myself to breathe, just put another ball in the court and keep doing the things that I do well," she added.

Gauff drew inspiration from the presence of gymnastics icon Simone Biles as she hauled herself out of trouble.

"I was just thinking if she can go on a six-inch wide beam and perform with all the things she's gone through, I can come out here on court and hit a ball," said Gauff.

The American plays Poland's Magdalena French in round three and could run into Naomi Osaka in a blockbuster last-16 clash featuring two former US Open champions.

Osaka impressed in a 6-3, 6-1 win over American Hailey Baptiste.

The Japanese star has not gone beyond the third round of a major since winning the last of her four Grand Slams at the 2021 Australian Open.

Asked if she feels ready to make another deep run in New York, she remained coy.

"I don't make it my business to know anymore. I kind of just leave it up in the air," said Osaka.

"For me, I realise that I've done everything that I could. I've trained really hard. I practised really hard. If it happens, it happens."

Osaka will meet Australian 15th seed Daria Kasatkina in the last 32.

Swiatek started Thursday's action on Arthur Ashe by fending off the Netherlands' Suzan Lamens 6-1, 4-6, 6-4.

World number two Swiatek looked to be cruising as she led by a set and a break but stumbled before eventually seeing off the 66th-ranked Lamens.

"It wasn't the easiest match. It got a bit complicated in the second set, but I'm happy that I could reset and start playing better in the third set," said Swiatek.

Swiatek, the 2022 US Open champion, has won 16 of 17 matches following titles at Wimbledon and Cincinnati. Shes faces Russian 29th seed Anna Kalinskaya for a spot in the last 16.

Czech 11th seed Karolina Muchova, a semi-finalist the past two years here, edged past Sorana Cirstea in three sets.

L.Nguyen--SFF