For an hour or so on the world’s biggest stadium court, Australian bolter Li Tu had Spanish sensation Carlos Alcaraz scrambling and the Arthur Ashe Stadium crowd chanting his surname in approval as he launched an audacious bid for a stunning upset.

It was already an exceptional day for Australian men, with six players including Alex de Minaur and Thanasi Kokkinakis progressing in fine fashion, but for Tu to press the reigning Roland Garros and Wimbledon champion added another layer of excitement.

Ultimately the 28-year-old qualifier’s bid fell short when he was beaten 6-2 4-6 6-3 6-1 in 2hr 42min, but Alcaraz was among those who left the world’s biggest stadium court convinced it was not the last tennis would see of the plucky South Australian.

“Obviously it surprised me a little bit. The first set it was obvious he started the match nervously,” he said.

“After the first set, he grew up and started to enjoy it. He played great tennis. He is a great player. I was surprised … and I am going to follow his results from now because I am pretty sure that if he is playing at this level, I am going to see him around very soon.”

Tu, who received a wildcard into the 2021 Australian Open and qualified for the US Open with some strong form last week, told Nick Kyrgios in a pre-match interview for ESPN he was hoping to have fun and was looking forward to treasuring the experience.

He certainly did that. And so did most of the other Aussie men in action on the second day at Flushing Meadows.

After Tu’s old junior teammate Kokkinakis set the tone for a great day with a massive upset of Stefanos Tsistsipas, de Minaur returned to winning form with a typically courageous win.

But de Minaur, who defeated Marcos Giron 6-3 6-4 5-7 6-4, conceded he is taking a step into the unknown every time he steps on to the court and is restricted in his movement given the hip injury which forced to him to forfeit a Wimbledon quarterfinal is still troubling him.

Playing in his first singles match since withdrawing before playing Novak Djokovic, the No.10 rallied strongly under pressure early in the fourth set against an American who had beaten him in three of their four previous outings and recently claimed an ATP Tour title.

“So this one meant a lot, just to be out there competing, you know, giving myself a chance to to play,” he said.

“And it was never going to be easy with all things considering, but (I am) very happy I was able to … get the win. Obviously (I) felt a lot of emotions that I haven’t felt in a while.”

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The 25-year-old was not as sharp as he had been in runs to the quarterfinals at Roland Garros and Wimbledon this year and said later he had been forced to play within himself, which goes against his ethos.

“It’s super hard. I mean … the actual concept of not trying to retrieve every single ball that’s out there on the court, it is tough, because I’ve been brought up with just going out there and trying to make every single ball,” he said.

“(Now) I’ve got to play a certain type of way to look after myself. It’s also quite difficult. So all of a sudden, I’m having to think a lot more than I’m used to, and it makes it a lot tougher.”

The challenge for de Minaur, who played a doubles match at the Olympics, is to freshen up for his second round match against Finnish qualifier Otto Virtanen, who is more talented than his ranking suggests.

Shivering during his press conference after a prolonged ice bath, he admitted that he was not sure how he will wake up tomorrow.

“It’s not 100 percent but it’s something that I knew was going to be the case. So it’s about learning to deal with it, play with it, have low expectations and just be mindful of it, because it’s still there,” he said.

“Honestly, the uncertainty of knowing when I’m gonna feel 100 per cent, still a lot is unknown at this stage.”

But after reaching the last 16 last year, it is another step in the right direction for the Davis Cup leader on a day where compatriots Kokkinakis, wildcard Tristan Schoolkate, Jordan Thompson, Max Purcell and Chris O’Connell also progressed.

It means eight Australian men are through to the second round after the opening day wins of Alexei Popyrin and Rinky Hijikata.

No Australian women progressed on the second day, with Ajla Tomljanovic and Maya Joint to play their second round matches on Wednesday in New York. Ten of the 20 Australians to reach the main draw in New York have progressed.

Kokkinakis, understandably, was thrilled after his 7-6 (5) 4-6 6-3 7-5 victory in 3hr 54minover the dual-grand slam finalist Tsitsipas and later described it as the biggest grand slam win of his career.

The triumph over the No.11 seed was just his second ever in New York and his first since 2019, though Kokkinakis has only managed to play five prior US Opens in the decade since he made his grand slam debut in Melbourne in 2014.

Kokkinakis, who will play Zizou Bergs in the second round, reaped rich rewards from both his powerful serve and also thunderous forehand, weapons which he put to good use against the No.11 seed in a highly-entertaining but also extremely physical match which saw both players receive medical treatment at different stages.

“It is a massive relief. I am super, super pumped,” he said.

“I’ve lost some tight ones but I am starting to get on the winning end of them now. I took a little bit of a break from tournaments after Montreal and just went to Florida, to Bradenton, and if anyone has been there, you there is not a whole lot to do there but train.

“That was what my goal was, to set myself up for moments and matches like this and (I’m) super happy it paid off.”

Western Australian wildcard Tristan Schoolkate, meanwhile, pulled off a massive comeback to defeat Japan’s Taro Daniel 4-6 4-6 6-4 7-6 (6) 6-4 in 3hr 49min.

The 23-year-old, who crowd-funded in the infancy of his professional career in order to raise enough money to travel to low-tier tournaments, raised his arms in delight to a roaring crowd on Court 16 after winning on his grand slam debut.

The aggressive all-court player, who is ranked 193, who has earned just over $500,000 in his career to date, will pocket at least $200,000 for reaching the second round in New York.

“It is massive, first of all to have the opportunity to play, I’m obviously grateful for that and to go one step further again, hopefully I can continue on,” he said.

“Things have changed a little bit. I started on my own from when I turned 18 and playing in the junior events, I had to do GoFundMe pages to help pay for things. My family does not come from a lot of money.

“Coming into the pros, this is by far the biggest cheque I have received. Hopefully I can continue on and it gets bigger and bigger, but it all goes back into your tennis. It looks like a big number on the prize money cheque, but you’ve got plenty of expenses on the road. It is obviously great and it will help propel me forward.”

He faces an extremely difficult test in his second round against highly-promising Czech Republic player Jakub Mensik, who thrashed 19th seeded Canadian Felix Auger-Aliassime 6-2 6-4 6-2. The winner of that clash will play Kokkinakis in the third round should he progress.

Jordan Thompson, who missed out on a goal of being seeded in a grand slam for the first time but one ranking, enjoyed a far easier progression when outclassing Frenchman Constant Lestienne 6-1 6-3 6-2. His prize is a second round outing against Polish star Hubert Hurkacz.

Purcell joined them when defeating compatriot Aleks Vukic, who rolled an ankle in the second set, 7-5 6-4 6-3 in 2hr 15min and awaits the winner of a clash between America’s 14th seed Tommy Paul and Lorenzo Sonego.

The Wimbledon doubles champion had been unsure how he would fare after hurting an ankle in Cincinnati and withdrew from a tournament last week as a precaution, but said he started to feel better a few days from the major beginning.

“There was a massive difference from Sunday to Monday and I was like, ‘OK, actually, I feel like I can win a match now’. So no, I didn’t know (this form) was coming,” he said.

“After the first game where I held and hit a few good balls from the back (of the court) and felt comfortable, I was like, ‘Alright, I can definitely do this.’”

O’Connell, who endured some injury struggles midway through the year, performed strongly to oust 26th seed Nicolas Jarry 6-4 6-3 4-6 6-3. He plays Italian qualifier Mattia Bellucci on Thursday.