US Open 2021: Men's singles power rankings

World No. 1 Novak Djokovic will look to become the first man since Rod Laver in 1969 to complete the Calendar Slam by winning the US Open, which kicks off on Monday.

Scheduled to take place at the Billie Jean King National Tennis Center in New York from August 30 - September 12, the year's final Major guarantees a fortnight of enthralling tennis action.

In the absence of Rafael Nadal and Roger Federer, the Next Gen, led by the likes of Daniil Medvedev and Alexander Zverev, are expected to pose the biggest challenge for Djokovic.

Also featuring in the men's singles draw are a slew of big names who have performed well on the North American hardcourts in the past.

Here, we rank the top eight contenders for the title based on their performances in the US Open series over the last three years.

Note: The following formula was used to calculate the power rankings for this year's US Open: (1x points earned in the 2021 USO series + 0.5x points earned in the 2020 USO series + 0.25x points earned in the 2019 USO series).

Only points earned by reaching the Round of 16 or further at a tournament counted towards the rankings. This was done to avoid giving undue advantage to seeded players who received early round byes in the ATP 250, 500 and 1000 tournaments.

#8. Pablo Carreno Busta

Pablo Carreno Busta at the 2021 Olympics.

Pablo Carreno Busta, who leads the Spanish charge in the absence of Rafael Nadal, will be hoping to replicate his success from last year's US Open. The World No. 12 reached the semifinals at Flushing Meadows last year, posting wins over the likes of Novak Djokovic (who was defaulted) and Denis Shapovalov along the way.

After claiming the bronze medal at the Olympics in Tokyo, Carreno Busta reached the quarterfinals in Cincinnati, which should hold him in good stead for the US Open.

#7. Jannik Sinner

Jannik Sinner at the 2021 Truist Atlanta Open.

Jannik Sinner's run to the title at the Washington Open earlier this month was enough to catapult him into seventh spot on the list. The youngster was in fine form throughout the week in DC, scoring resounding wins over a number of Next Gen stars.

He hasn't been able to replicate that form in the last couple of weeks, but he remains a big threat.

#6. Reilly Opelka

Reilly Opelka at the 2021 National Bank Open.

Reilly Opelka is in the midst of a breakthrough season. The 23-year-old's power-packed game has helped him stage deep runs at hardcourt tournaments this year and he will be brimming with confidence in the lead-up to the year's final Slam.

Opelka was especially impressive in Toronto, where he took down the likes of Nick Kyrgios and Stefanos Tsitsipas en route to the final. Spearheading the American charge, Opelka will look to make it to the second week in New York for the first time in his career.

#5. Andrey Rublev

Andrey Rublev at the 2021 Western & Southern Open.

After disappointing results at the Olympics and Toronto, Andrey Rublev finally found some form at the Western & Southern Open, where he advanced to the final. The Russian looked confident on the hardcourts in Cincinnati and will be keen to carry the momentum into the US Open in New York.

Rublev has done well at Flushing Meadows in the past. He made the quarterfinals in 2017 and 2020, and the fourth round in 2019. Given the right kind of draw, the 23-year-old Russian could deal some damage this year as well.

#4. Novak Djokovic

Novak Djokovic with the trophy at the 2018 US Open.

Novak Djokovic occupies the fourth spot on this list due to the fact that he has not played a single warm-up tournament this year.

Djokovic might be the overwhelming favorite to take home the title on paper, but his most recent results at the US Open will not fill him with too much confidence.

A mid-match retirement and default in the 2019 and 2020 editions respectively, mean the World No. 1 has not progressed past the fourth round at Flushing Meadows since 2018.

That said, the disappointing end to his last two US Open campaigns may fuel Djokovic's hunger for a fourth title in New York. The Serb is the most successful player in New York from the current field, and if he is in prime condition, he will be a hard man to stop.

#3. Stefanos Tsitsipas

Stefanos Tsitsipas at the 2021 Western & Southern Open.

Stefanos Tsitsipas is one of the few players on the men's side to have posted consistent results on the American hardcourts over the last couple of years. Semifinal finishes in his last three Masters 1000 appearances in the US Open series have seen him move up to No. 3 on the list.

Unfortunately for the Greek, he has never carried his Masters 1000 form into the US Open, where he is yet to make the second week. Tsitsipas is in fine form heading into the tournament this year and will be looking to put an end to that dismal streak.

#2. Alexander Zverev

Alexander Zverev with the trophy at the 2021 Western & Southern Open.

Alexander Zverev came agonizingly close to winning his first Grand Slam title at the US Open last year, but it wasn't meant to be for the German as he was defeated by Dominic Thiem in a five-set final.

Zverev will be determined to go one step further this year and get his hands on the trophy.

The German has been in ominous form in recent weeks. He defeated Novak Djokovic en route to the gold medal in the Olympics and then produced a dominant run in Cincinnati to claim his fifth Masters 1000 title.

#1. Daniil Medvedev

Daniil Medvedev at the 2019 US Open.

With a US Open final and two Masters 1000 titles to show for in the past couple of years, Daniil Medvedev is far and away the No. 1 on this list. The Russian is a force to be reckoned with on the American hardcourts.

Medvedev has looked rock-solid in the lead-up to the US Open, taking home the title in Toronto and reaching the semifinals in Cincinnati. The Russian could well be Djokovic's biggest threat in New York this year.

Honourable mentions

Experienced players like Roberto Bautista Agut and Grigor Dimitrov, as well as talented youngsters in the form of Denis Shapovalov, Hubert Hurkacz and Casper Ruud, could spring a surprise or two.