In this June 14, 2020 photo, Serbian tennis player Novak Djokovic returns the ball to German tennis player Alexander Zverev during their single match at the Adria Tour, Novak Djokovic's Balkans charity tennis tournament in Belgrade. (ANDREJ ISAKOVIC / AFP)

MUMBAI - Men’s governing body ATP on Monday unveiled a revised system for calculating world rankings when the season resumes in August following a five-month suspension due to the COVID-19 pandemic.

The ATP’s rejigged calendar for the year includes two Grand Slam events in the US Open and the French Open and three Masters 1000 events

Traditionally the ATP rankings operates on a formula of 18 best results over 52 weeks but will now cover a 22-month period from March 2019 through December 2020.

While the new model provides impetus for players to improve results from their 2019 performance, it will also provide stability to those who choose not to play due to the pandemic as they would not need to defend points.

The ATP’s rejigged calendar for the year includes two Grand Slam events in the US Open and the French Open and three Masters 1000 events.

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Novak Djokovic, world number one

The Serb will be favourite to keep his number one ranking at the end of year as he retains the points he earned from his 2019 Wimbledon win till 2021 with the grasscourt Grand Slam cancelled due to the pandemic in 2020.

Djokovic will also keep points from his Madrid and Paris Masters wins even if he decides to skip the events in 2020 or fares badly in them.

He could also strengthen his position at the top of the rankings by improving on his fourth round exit at the US Open and defeats in the semi-finals of the French Open and the Cincinnati Masters.

In this Feb 5, 2020 photo, Rafael Nadal of Spain sets off to return the ball to retired compatriot David Ferrer (unseen) during an exhibition game to inaugurate the Rafa Nadal Academy Kuwait, at Shaikh Jaber Al Abdullah Al Jaber Al Sabah International Tennis Complex in the Kuwaiti capital. (YASSER AL-ZAYYAT / AFP)

Rafa Nadal, world number two

The Spaniard had to previously defend more than 5,000 points over six weeks, having won the Grand Slams in New York and Paris in 2019 and also the Rome Masters. But he will now get to keep all those points even if he does not hit a ball.

If Nadal decides to travel to the United States for the hardcourt season, he would have a chance to pick up points from the Cincinnati Masters after he skipped the event in 2019.

In this June 14, 2020 photo, Austrian tennis player Dominic Thiem returns the ball to Bulgarian tennis player Grigor Dimitrov during their single match at the Adria Tour, Novak Djokovic's Balkans charity tennis tournament in Belgrade. (ANDREJ ISAKOVIC / AFP)

Dominic Thiem, world number three

Thiem will retain the points he gained from his appearance in last year’s French Open final and his semi-final appearance at the Madrid Masters.

The Austrian will also have the scope to improve on his first round exit at the US Open and the early loss in Rome.

In this Feb 7, 2020 photo, Switzerland's Roger Federer plays a return to Spain's Rafael Nadal during their tennis match at The Match in Africa at the Cape Town Stadium, in Cape Town. (RODGER BOSCH / AFP)

Roger Federer, world number four

The biggest gainer from the revised rankings will be Federer, with the Swiss ruling himself out of the rest of the season after undergoing a second knee surgery during the year.

The 20-times Grand Slam winner has not played since his semi-final defeat by Djokovic at the Australian Open and would be able to keep most of the points from 2019 that he would have otherwise lost in normal circumstances.

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In this Jan 27, 2020 photo, Russia's Daniil Medvedev serves against Switzerland's Stanislas Wawrinka during their men's singles match on day eight of the Australian Open tennis tournament in Melbourne. (MANAN VATSYAYANA / AFP)

Daniil Medvedev, world number five

The Russian has the chance to make significant gains during the rest of the year, having lost in the first round at the Madrid and Rome Masters and also the French Open in Paris.

If the results do not go his way, Medvedev will still have the cushion of the significant points he earned by winning the Cincinnati Masters and reaching the U.S. Open final in 2019.