Dominic Thiem defeated J.J. Wolf to set up a showdown with top seed Grigor Dimitrov in the second round of the Winston-Salem Open.

Thiem showed signs of returning to his best with runs to the last eight or better in three tournaments in July, but the 2020 US Open winner was in danger of falling at the first hurdle in North Carolina when he lost the first set against the American wildcard.

But Thiem, a debutant in the competition, bounced back, and after a long rain delay he prevailed 6-7 (5-7) 7-5 7-6 (8-6), and he will now face Dimitrov, who is seeking a first trophy since 2017.

The Austrian had to save two match points during a last-set tie-break, and said afterwards: "First of all I'm super happy to get that win, [my] first win on hard courts since a very long time, since March 2021, I guess.

"It was not easy at all today with the rain delay, coming back out there at 11:15 p.m. It was very late. I had trouble [getting] into the match again.

"But luckily I raised the level a little bit in the third-set tie-break and compared to Kitzbuhel, where similar stuff happened with the rain, the luck was on my side today."

Second seed Botic van de Zandschulp also learned of his last-32 opponent on Monday, with Tallon Griekspoor beating fellow lucky loser Taro Daniel 7-6 (7-3) 6-3.

Last year's beaten finalist Mikael Ymer ensured a safe passage through, meanwhile, thanks to a 6-2 6-3 victory against Federico Coria.

Australia's James Duckworth also advanced with a 4-6 6-3 7-5 (7-5) comeback win over compatriot Thanasi Kokkinakis, while Kyle Edmund saw off Michail Pervolarakis 6-2 7-5.

Sixth seed Nikoloz Basilashvili was a big-name exit, as he went down to Thiago Monteiro.

World number two Alexander Zverev has withdrawn from the US Open as he recovers from ankle surgery.

The German went under the knife after tearing all three of the lateral ligaments in his right ankle during his French Open semi-final against Rafael Nadal.

Zverev will not make his comeback at the final grand slam of the year in New York, as his withdrawal was announced on Monday.

The 25-year-old reached his only major final at Flushing Meadows two years ago, losing to Dominic Thiem.

Zverev stated after his operation that surgery was "the best choice" to ensure his ligaments heal properly and he could return to competition "as quickly as possible."

The US Open gets under way next Monday, with doubts remaining over whether Novak Djokovic will be able to play due to the 21-time grand slam champion opting against receiving a coronavirus vaccine.

Roger Federer looks bang on course to launch his comeback next month after the 20-time grand slam winner posted an encouraging video of a practice session on Sunday.

The Swiss turned 41 on August 8 and has not played a match since losing to Hubert Hurkacz in the quarter-finals at Wimbledon last year.

He has undergone knee surgery in the meantime, his third such operation inside two years, but is determined to resume his playing career and looked to be enjoying being back on court in a short clip posted to Instagram.

Federer is due to play in the Laver Cup, which will be staged in London from September 23 to 25, with Rafael Nadal, Andy Murray and Novak Djokovic set to join him in an illustrious Team Europe line-up.

It will be a reunion for the 'Big Four', who were once so dominant as a group, with Stefanos Tsitsipas and Casper Ruud also on the European team, which will be captained by Bjorn Borg.

Federer is then entered for the Swiss Indoors in his home city of Basel, where he has been champion 10 times previously and holds a remarkable 75-9 win-loss career record.

It remains to be seen whether that October 24-30 tournament is a farewell appearance, or another step towards playing regularly on the ATP tour once more.

At Wimbledon in July, Federer appeared at a parade of former champions and said he wished to play at the All England Club again, which points to him planning to play in the 2023 season.

"I hope I can come back here one more time," said Federer, an eight-time Wimbledon champion.

The prize pot for this year's US Open will top $60million for the first time in the competition's history, event organisers have announced.

The 2022 edition at Flushing Meadows gets under way on August 29 and runs for just under two weeks.

It was revealed on Thursday that $60m will be up for grabs, topping the previous record of $57.5m from last year, with both singles champions to receive $2.6m.

Players will be given $80,000 for making the main draw and $121,000 should they make it to the second round. Runners-up in the singles will pocket $1.3m.

In the doubles, the champions will receive $688,000, the runners-up $344,000 and the semi-finalists $172,000.

Taylor Fritz believes there would be no "harm" in Novak Djokovic competing at the US Open, although the American admits he is conflicted about whether he should be allowed.

Wimbledon champion Djokovic has his route to Flushing Meadows blocked by red tape at present, with the United States refusing to allow unvaccinated foreign visitors to enter the country.

US tennis authorities have pledged to adhere to government rulings surrounding COVID-19 protocols, despite including Djokovic on their entry list.

For Djokovic to be allowed into the United States, it appears he would require a change of policy from law-makers, or he would have to be considered suitable for an exemption.

Among those who would be eligible for such an exemption are "persons whose entry would be in the national interest".

With 21 grand slam titles, Djokovic sits second on the men's all-time list behind Rafael Nadal, who has 22 victories at the majors. 

And Fritz, ranked 13th in the world, said that while the situation is complicated, there is part of him that thinks Djokovic should be allowed to take part in the competition that starts in under a fortnight.

"It's tough," he said. "I think on one side of it, I think it's tough to make certain exceptions to the rules for certain people.

"I don't know how I feel about that, but then, at the same time, we're not the most COVID-safe country in general with how we are doing things.

"So it does seem like, what's the harm of letting the best player in the world come play the US Open?

"But like I said, at the same time, it's conflicting, because I don't know how I feel about making special exceptions just for one person because of who they are.

"So I see both sides of the argument, to be honest. It's tough to differentiate, obviously. It's good for every player if Novak is not in the draw."