The last time Australia had two men in the US Open fourth round, Lleyton Hewitt won the title.
And with his so-called "big brother" Jordan Thompson joining him in the last 16, Alex de Minaur says he won't be pushed around in his bold bid to follow in Hewitt's footsteps at Flushing Meadows.
Despite giving away three years, 15cm, 18kg and 12 rankings spots, de Minaur upset powerhouse Russian Karen Khachanov 6-4 0-6 4-6 6-3 6-1 to give Australia two second-week title hopes in New York for the first time since Hewitt and two-time champion Pat Rafter reached the same stage in 2001.
"It's amazing, these stats. I'm so happy that I'm able to do it with a fellow Sydneysider as 'Thommo,'" de Minaur said.
"Look, we're both out here getting some wins and I couldn't be happier for us both. Hopefully we can just keep it going."
De Minaur first met 26-year-old Thompson when he was 11.
"He's like a big brother for me," he said.
"It was just kind of amazing to see him kind of grow up and get to the point where he has gone and me trying to follow in his footsteps.
"We have had a lot of great memories in Davis Cup, as well, and that's definitely built our friendship for sure."
Lightweight only in physical comparisons, de Minaur had too many guns for Khachanov, overcoming a mid-match meltdown to progress to the last 16 for the second straight year after driving the big Russian mad with his relentless retrieving and counter-punching.
The 21st seed landed eight aces and 42 winners to seal victory after three hours and two minutes, emulating countryman Nick Kyrgios's five-set third-round triumph over Khachanov at the Australian Open in January.
"I was able to just be constant pressure throughout the whole match," de Minaur said.
"I felt like I didn't give him too many mistakes and I just made sure that he had to work in every one of his service games.
"I back my fitness in any match, so I knew I wasn't going to have problems physically so it was all about me mentally. I'm happy I won that battle."
At 193cm, Pospisil is another imposing figure who served notice with his own 7-5 2-6 4-6 6-3 6-2 comeback win over Spanish eighth seed and 2019 Wimbledon semi-finalist Roberto Bautista Agut.
"Well, obviously even though Vasek isn't a seed, he's definitely playing like a top seed," de Minuar said.
"He's taken out both Milos (Raonic) and Bautista. He definitely deserves to be there.
"He's a very, very dangerous player. He's obviously a very aggressive player. He's going to look to dictate a lot and try to take the net.
"I've just got to make sure I keep my depth, try not to get pushed around and, a little bit like today, try to stand my ground and hopefully dictate myself."
Both de Minaur and Thompson are eyeing maiden grand slam quarter-final berths.
Thompson faces No.27 seed Borna Coric on Monday after the Croatian saved six match points to oust Greek fourth seed Stefanos Tsitsipas in a five-set fourth-round thriller on day five.
HOW THE AUSSIES FARED ON DAY SIX OF THE US OPEN OPEN (PREFIX DENOTES SEEDING)
Men's singles, third round:
21-Alex de Minaur bt 11-Karen Khachanov (RUS) 6-4 0-6 4-6 6-3 6-1