Chris O'Connell has revealed the secret recipe to Australia's quiet tennis revolution as he plots to serve up one of the great US Open boilovers in New York.

O'Connell takes on world number one and reigning Australian Open champion Jannik Sinner hungry to secure a maiden berth in a grand slam second week.

The 30-year-old is among four Australian men in the third round at Flushing Meadows for the first time since 1997, joining ring leader Alex de Minaur, Alexei Popyrin and summer hitting partner Jordan Thompson. All four hail from the NSW capital.

Popyrin is the first to hit the court, taking on Novak Djokovic from about 10:15am (AEST) this morning.

Another four Sydneysiders — James Duckworth, Rinky Hijikata, Aleksandar Vukic and Max Purcell — were among 10 Australians ranked in the top 100 entering the Open for the first time since 1980.

O'Connell credits mateship and the good old-fashioned Aussie meat pie for the stunning renaissance.

"When we had the pre-season last year, and this year, there's heaps of guys floating around and they're all top-100 players, so we're just pushing each other," O'Connell said.

"It's a great atmosphere.

"Me and 'Thommo' we train a little bit at Collaroy so we've got a bit of a routine where we finished our session and we go across the road and there's a really good pie shop, like amazing pie shop.

"So we have a pie there and then we go for a swim at Long Reef.

"I mix it up all the time but I love the stock standard — just steak all the time, every Monday."

Thompson also swears by the award-winning shop, just around the corner from former Davis Cup captain Wally Masur's house on Sydney's northern beaches.

"That's definitely the secret, the Upper Crust across the road from the courts and then we go down for a swim and catch some waves with his brother as well and Maxi (Purcell)," Thompson said.

"So it was just a bit was a running joke; we can't wait to get back down there and wrap up the season after the US Open."

Business comes before pleasure, though, with Thompson also facing an Italian seed, world number 30 Matteo Arnaldi, for a place in the last 16.

"It's a huge opportunity for both of us, there's no denying that," said Thompson, who could earn a clash with de Minaur for a coveted spot in the quarter-finals.

De Minaur, even still playing less than 100 per cent fit in his first tournament back from the hip injury that forced him out of the Wimbledon quarter-finals, is favoured to take out British veteran Dan Evans in his third-round match on Louis Armstrong Stadium

O'Connell will be a big underdog against Sinner on Arthur Ashe Stadium, but has beaten the top seed — three years ago on a hard court in Atlanta.

Sinner won their more recent encounter in Miami earlier this year.

"So I got to see the improvements he's made," O'Connell said.

"At the same time I've improved but he's just tightened up his game a lot more.

"Still super aggressive, a great ball striker, but I didn't get as many errors in Miami as I did in Atlanta.

"When I did get over the top with him in Atlanta, I used my slice a lot. I served really well.

"I know I've got to serve really well if I'm going to have any chance. If you's serving well and holding, then it just makes life a lot more easier."

Men's singles, third round

Chris O'Connell v 1-Jannik Sinner (ITA) — 4am Sunday AEST

Jordan Thompson v 30-Matteo Arnaldi (ITA) — 7am Sunday AEST

10-Alex de Minaur v Dan Evans (ENG) — 9am Sunday AEST

AAP