'It's sick': Aussie tennis battlers march on at US Open

Now the odd couple share an improbable place in the US Open second round after scrapping and diving around Flushing Meadows like Boris Becker in pursuit of grand slam glory.

"Yeah, it's really nice. I'm always rooting for the Aussie boys and it's nice to see a couple get over the line, especially Tristan. We've known each other for so long," Sweeny told AAP.

The 25-year-old was sporting the scars of battle, a massive ice bag on his right elbow after throwing himself desperately at volleys on court 7 on Tuesday (Wednesday) AEST).

But Sweeny said it was "all good, it was worth it" after securing a $US190,000 ($A266,000) pay day for posting his maiden grand slam win outside of Australia.

"The lump's usually standard, but I haven't been icing it. When I dive, I land on the same spot every time, so it just keeps popping up," Sweeny said after advancing when the equally theatrical Frenchman Corentin Moutet retired with injury while trailing 7-6 (7-4) 6-4 3-0.

"I've got like permanent fluid build-up there. Sometimes I can't help it - I'm in the air before I even know it."

Schoolkate was on his own natural high after finishing off American qualifier Nishesh Basavareddy 7-6 (7-4) 3-6 6-3 6-4 in a tick over three hours, then celebrating like Lleyton Hewitt after giving Australia at least seven players in the second round.

"The atmosphere's pretty cool. They're chanting 'USA, USA'. It's sick," Schoolkate said.

"I haven't lost in the first round here yet, so, it's a good start. I'm coming through qualies this time and that gave me a lot of confidence and I played a really good match. Probably the best match I've played here."

The 25-year-old said his latest triumph was even more special, happening on the same day as Sweeny's big breakthrough.

"It was epic," Schoolkate said.

"I couldn't help but sit and look at the scoreboard the whole time and see his score pop up. So I was pretty pumped.

"We were both amped when we saw each other this morning and, yeah, we hoped it was going to be a good day for us."

Fittingly, the two good mates both play quality Italians next. 

Schoolkate faces fifth seed Fabio Cobolli, the 2026 French Open runner-up, while Sweeny takes on world No.14 Lorenzo Musetti.

"I'm really excited to play Musetti," Sweeny said.

"It's going to be a great match. He's obviously one of the world's best players and I'm really excited to take it to him."

Sweeny, who only stands 170cm high, and Schoolkate join fellow Australians Alexei Popyrin, James Duckworth, Taylah Preston, Kim Birrell and Maya Joint in round two.

Men's sixth seed Alex de Minaur and women's Australian No.1 Daria Kasatkina will likely have to wait another day to try to follow suit after more rain in New York wiped out the day-three night session.

Kasatkina was trailing Spain's former world No.2 Paula Badosa 6-1 1-2 when she was forced off court, while de Minaur's first-round clash with Italian qualifier Andrea Guerrieri hadn't even started.

The luckless Thanasi Kokkinakis had to pull out of his scheduled opener against Spanish 12th seed Rafael Nodar with an ankle injury.