There are many intriguing storylines to watch for in the 2021 ATP Tour season. Novak Djokovic and Rafael Nadal lead the way as the Top 2 players in the ATP Rankings and both men will be chasing history in 2021. The pair was given an early warning for the coming season at the 2020 ATP Finals by Dominic Thiem and Daniil Medvedev, who both earned victories against the Top 2 stars en route to the championship match.

World No. 3 Thiem and London champion Medvedev lead a growing list of challengers to the dominance of Djokovic and Nadal. That group includes former Nitto ATP Finals champion Stefanos Tsitsipas and 2020 Most Improved Player of the Year Andrey Rublev.

NOVAK’S PUSH: After becoming only the second man to hold the top spot in the ATP Rankings for 300 weeks on Dec.21, Djokovic will have his sights set on one of the most prestigious records in tennis in the first quarter of the 2021 ATP Tour season. The Serbian is currently nine weeks behind Roger Federer’s record of 310 weeks at the top of the sport.

Djokovic, who leads longtime rival and World No. 2 Nadal by 2,180 points, will pass Federer’s mark if he can maintain his position at the top of the sport until March 8.

In 2020, Djokovic tied his idol Pete Sampras’ record of six year-end World No. 1 finishes. The 33-year-old will be aiming to take sole ownership of that record by completing back-to-back year-end World No. 1 finishes for the third time.

WILL RAFA BOUNCE BACK?: Rafael Nadal equalled Federer’s record haul of 20 Grand Slam trophies at Roland Garros in 2020 and finished the year with a record 12th Top 2 finish in the ATP Rankings. The question is, will the Spaniard be able to bounce back to the top spot in 2021?

The 20-time major champion’s hopes of returning to the top position will rest on his ability to continue adding to his impressive Grand Slam and ATP Masters 1000 trophy collections.

IS IT THIEM’S TIME: After becoming the first player in six years to win his maiden Grand Slam title at the 2020 US Open, Thiem defeated his main rivals Djokovic and Nadal en route to his second consecutive runner-up finish at the ATP Finals in London. The Austrian is now within touching distance of a major milestone in 2021. Thiem currently sits just 725 ATP Ranking points behind World No. 2 Nadal. One of the keys for Thiem to surpass that will be his ability to maintain his recent success against his main rivals. Since the start of the 2019 ATP Tour season, Thiem has compiled a 9-3 record against Federer (3-0), Nadal (3-1) and Djokovic (3-2).

CAN MEDVEDEV MAINTAIN MOMENTUM?: Daniil Medvedev ended 2020 as the in-form player on the ATP Tour. The Russian claimed back-to-back titles at the Paris Masters and the ATP Finals to finish the year on a 10-match winning streak, which included seven Top 10 victories.

If Medvedev can translate his indoor form to outdoor success, he could join Thiem as a challenger to Djokovic and Nadal’s stranglehold on the Top 2 positions in the sport. The World No. 4 has started his season strong in the past. He opened his 2020 campaign with seven wins from nine matches in Australia.

Janko Tipsarevic, who was part of Serbia’s 2010 David Cup-winning team says: “Novak Djokovic, Rafael Nadal and Roger Federer raised the ladder so much that it is necessary to dominate (on all surfaces) in relation to the previous generation.”

The Serbian predicted a bright future for Medvedev, but added that Medvedev needs to learn to do better on clay surface.

“Medvedev is an amazing player,” Tipsarevic said. “It is not a question of whether he will win the Grand Slam title, since he will, it is not a question of whether he will be number one -- he will at one point.”