The lure of competing with the tennis heavyweights at the elite season-ending championship is pushing Alex de Minaur through the pain barrier in New York.
De Minaur candidly admitted he was far from fully fit after returning from a hip injury to safely progress to the second round of the US Open and is no guarantee to continue at Flushing Meadows.
Lightning speed and agility are the world No.10's chief weapons, and de Minaur is lamenting having to play compromised.
"It's super hard. I mean, for me, the actual concept of not trying to retrieve every single ball that's out there on the court, it is tough," he said ahead of his scheduled second-round clash with Finnish qualifier Otto Virtanen.
"I've been brought up with just going out there and trying to make every single ball back.
"So when you've got to play a certain type of way to look after yourself, it's also quite difficult. All of a sudden I'm having to think a lot more than I'm used to, and it makes it a lot tougher.
"So I'm learning to deal with it, play with it, have low expectations and just be mindful of it because, yeah, it's still there.
"It's not 100 per cent, but it's something that I knew was going to be the case."
De Minaur had a light practice hit on Wednesday (Thursday AEST), but his camp conceded he still wasn't certain of taking the court against Virtanen.
If he doesn't, the Australian No.1 at least picked up precious points with his four-set first-round win over Marcos Giron to move provisionally into eighth spot in the season-long Race to Turin standings.
The top eight players will feature at the ATP Finals in Italy from November 10-17.
Runner-up to Stefanos Tsitsipas and now world No.1 Jannik Sinner respectively in the 2018 and 2019 Next Gen Finals, de Minaur is desperate to make the real thing this year.
Otherwise the 25-year-old might not have played the US Open at all, only seven weeks after tearing a hip muscle at Wimbledon and being forced to withdraw from a blockbuster quarter-final with Novak Djokovic.
"The goal, obviously, is Turin, and missing a lot of weeks on the tour, a lot of big tournaments, is very detrimental to your chances of making Turin," de Minaur said after beating Giron.
"Because they're big points on offer and big events. So I wanted to make sure I was coming back as as soon as possible, but at the same time knowing that I'm not 100 per cent, it's not easy."
De Minaur hit a career-high No.6 in the world after reaching back-to-back grand slam quarter-finals for the first time at Roland Garros and Wimbledon.
He will leave New York ranked 11th or lower unless he wins at least another match.
De Minaur is one of six Australians scheduled for second-round action on day four after eight Aussie men won their openers in New York for the first time since 1975.
All six have a decent chance of going further and joining Alexei Popyrin in the last 32.
Only Jordan Thompson, who is up against world No.7 Hubert Hurkacz, and Max Purcell, who plays the 14th-ranked Tommy Paul, are playing seeds.
After taking out the 11th-seeded Tsitsipas in the biggest grand slam win of his career, Thanasi Kokkinakis next faces world No.34 Nuno Borges.
Chris O'Connell's reward for ousting 26th seed Nicolas Jarry is a huge opportunity against world No.101 Mattia Belluci.
And Tristan Schoolkate takes on the 65th-ranked Jakub Mensik hoping to cash in further on his wildcard entry.
Popyrin will play defending champion Djokovic on Friday (Saturday AEST) for a place in the last 16.
AUSSIES IN ACTION ON DAY FOUR OF THE US OPEN ON THURSDAY (FRIDAY AEST):
Men's singles, second round
10-Alex de Minaur v Otto Virtanen (FIN)
Jordan Thompson v 7-Hubert Hurkacz (POL)
Thanasi Kokkinakis v Nuno Borges (POR)
Max Purcell v 14-Tommy Paul (USA)
Chris O'Connell v Mattia Belluci (ITA)
Tristan Schoolkate v Jakub Mensik (CZE)
