Il Nuovo Postiglione - Sinner tested at US Open as Gauff cruises into last 16

Sinner rallied from a set down to beat Shapovalov 5-7, 6-4, 6-3, 6-3 and is trying to become the first man to retain the title in New York since Roger Federer in 2008.

"A very tough match today. I've known Denis for quite a long time. I knew that I had to play at a very high level," said Sinner, who lost his previous meeting with Shapovalov at the 2021 Australian Open.

World number one Sinner awaits the winner of the evening session match between US 14th seed Tommy Paul and Alexander Bublik, the 23rd seed from Kazakhstan.

"Week two is completely different. It's always a great sight that I'm still here. It's getting tougher and tougher, also physically and mentally," said Sinner.

Italian 10th seed Lorenzo Musetti advanced when compatriot Flavio Cobolli retired with an arm injury while trailing 6-3, 6-2, 2-0.

"I didn't want to finish like that, especially against Flavio. He's probably one of my best friends on tour," said Musetti after making the US Open last 16 for the first time.

Musetti, a potential quarter-final opponent for Sinner, will next play the unseeded Jaume Munar.

Swiss qualifier Leandro Riedi, the world number 435, became the lowest-ranked man to reach the fourth round of a major since 2002 as Polish opponent Kamil Majchrzak retired after eight games due to injury.

Hong Kong's Coleman Wong saw his brave run ended by a five-set loss to 15th seed Andrey Rublev.

The 21-year-old Wong had become the first player from Hong Kong ever to win a Grand Slam singles match in the Open era.

Alexander Zverev meets Felix Auger-Aliassime under the lights on Louis Armstrong Stadium later on Saturday.

- Gauff at ease -

Gauff began the day on Arthur Ashe Stadium and swept past Polish 28th seed Magdalena Frech 6-3, 6-1 in her most polished display of the tournament to boost her hopes of collecting a second US Open title and third Grand Slam overall.

After battling to a tearful victory in the previous round, a much more composed Gauff dispatched Frech with relative ease.

"I thought today I played well," said Gauff, through to the last 16 in New York for the fourth year in a row.

"It's been an emotional week, but I think I needed those tough moments to move forward. I was putting so much pressure on myself.

"I think today showed I was really having fun out there."

Gauff heads into a blockbuster showdown with former world number one Naomi Osaka after the Japanese star beat Australian 15th seed Daria Kasatkina in three sets.

Four-time Grand Slam champion Osaka won 6-0, 4-6, 6-3 to continue her best US Open showing since winning the tournament for the second time in 2020.

"I don't think I played that well, but I think mentally I was just trying to, like, fight for everything," said Osaka.

"I know that it was a little bit of an emotional roller coaster."

Karolina Muchova won an all-Czech encounter with Linda Noskova as she came from a set down to prevail 6-7 (5/7), 6-4, 6-2. Ukrainian 27th seed Marta Kostyuk overcame France's Diane Parry in three sets.

World number two Iga Swiatek opens the night session on Arthur Ashe against Russian 29th seed Anna Kalinskaya.

M.Dodaro--INP