From Novak Djokovic to Rafael Nadal, here are eight men to watch at US Open

The world number one is in hot pursuit of his second straight US Open title and third major of the season.

Despite his surprise loss in the semi-finals of Cincinnati Masters, Djokovic is charging up the ranks of the all-time greats.

Having saved two match points to beat Roger Federer in the Wimbledon final, Djokovic increased his haul to 16 Grand Slam titles. 

He is now only two behind Rafael Nadal and four shies of Federer's total.

The Spaniard’s toughest challenge these days may be staying fit on the hard courts. 

The 33-year-old successfully defended his Rogers Cup title earlier this month but then pulled out of the Cincinnati Masters due to fatigue. 

If Nadal, who was forced to retire during last year’s US Open semi-final with knee pain, feels healthy then he could enjoy another run to the title he last won in 2017. 

The US Open represents the longest drought of all the majors for Federer, who last won at Flushing Meadows in 2008.

After failing to convert two championship points against Djokovic in the fifth set of last month's Wimbledon final, the Swiss will be desperate to heal his wounded pride by winning a sixth title at Flushing Meadows - and 21st major overall. 

Dominic Thiem has struggled to leave a mark at the other three slams, with a quarter-final showing at Flushing Meadows in 2018 being his best effort at a major that is not played on clay.

After falling in the first round at Wimbledon for the second year running, he will be hoping to live up to at least his seeding over the next fortnight. 

Thiem's victory in New York made him the first new Grand Slam winner in six years and Medvedev is among those hoping it's another sign the Big Three era is fading. 

The 24-year-old Russian is another player who has been knocking on the door, after he reached the 2019 US Open final -- losing in five sets to Nadal -- and the last four in New York in 2020.

Medvedev went on a tear at the end of last season, winning 10 matches in a row and lifting the Paris Masters and ATP Finals trophies.

After beating Djokovic and Nadal in London, and edging a gripping final against Thiem, Medvedev became the first player to account for all of the world's top three at the season finale.

Medvedev, who had a tour-leading 59 victories in 2019, has won all nine of his career titles on hardcourts, and will now want to improve on his fourth-round showings on his last two visits to Melbourne Park.

Zverev has all the weapons to succeed on the big stage but has so far suffered stage fright every time he shows up at a Grand Slam event.

Two quarter-final appearances at the French Open is the best Zverev has been able to muster at the majors.

Long tipped as a future Grand Slam champion, Zverev needs to step up sooner rather than later if he wants to break the stranglehold of tennis' Big Three of Djokovic, Nadal and Federer - who between them have won the last 11 slams.

Zverev's best showing in New York was a run to the third round last year and have fallen in the first round at Wimbledon this year, he will be eager to avoid suffering the same fate again. 

Despite early-round losses Montreal and Cincinnati, Nishikori has been consistent at the majors this year, reaching the quarter-finals of all three and losing only to tennis' Big Three.

As he has been drawn in the same half as Federer and Djokovic, Nishikori will be hoping another grand slam run does not end in the quarter-finals, where he is due to face the Swiss. 

Nick Kyrgios will not represent Australia at this year's Olympics in Tokyo because he does not want to compete if there are no fans in the stands.

"It has been my dream to represent Australia at the Olympics and I know I may never get that opportunity again," the 26-year-old Kyrgios wrote on social media.

"But I also know myself. The thought of playing in front of empty stands just doesn't sit right with me. It never has."