Male tennis players who made their breakthrough in 2021

The ATP tour continues to be led by Novak Djokovic as fellow Big 3 members Roger Federer and Rafael Nadal are still grappling with injuries. Of the younger players, Daniil Medvedev won his first Grand Slam this year, while Stefanos Tsitsipas and Alexander Zverev also continued to make deep runs and win big tournaments.

The 2021 season also saw the rise of new talent, signaling that they're ready to compete with the big guns. Let's take a look at the players who made their breakthrough this year:

#1 Jannik Sinner

Jannik Sinner at the 2021 US Open.

Jannik Sinner showed his potential when he reached the quarterfinals at Roland Garros last year, but he took his career to the next level in 2021.

The Italian made two fourth-round appearances at Grand Slams, a maiden final at Masters 1000 level, won four titles, and made his debut at the ATP Finals, albeit as an alternate. He ended the year ranked in the top 10, concluding a successful season for the young Italian.

It's only Sinner's second year on tour, but he has already achieved a lot in his breakthrough season and looks poised for future success.

#2 Casper Ruud

Casper Ruud at the 2021 ATP Finals

While Casper Ruud underperformed at the Grand Slams after a fourth round appearance at the Australian Open, his consistent performances at other events earned him a spot on the list.

With the exception of the Indian Wells Masters, where he reached the fourth round, Ruud made the quarterfinals or better at all other ATP 1000 events he competed in. He won five titles during the year and reached the semifinals of the ATP Finals on his debut, while ending the season ranked number eight.

Ruud had won a total of 60 matches over the course of his previous four seasons on tour, and this year he finished with a record of 57-17, a massive improvement.

#3 Hubert Hurkacz

Hubert Hurkacz at the 2021 Wimbledon.

Hubert Hurkacz has been touted as one of the most promising next-gen players on the ATP circuit, and this year he finally showed us why. The 24-year-old won three titles this year, including his first at the ATP 1000 level.

While he had a rough patch following that huge victory, with a few early losses, he had another breakthrough as he reached his first Grand Slam semifinal at Wimbledon. He defeated his childhood idol Federer in the quarterfinals, even handing the Swiss ace a bagel, a very rare occurrence.

Following his quarterfinal run at the Indian Wells Masters, Hurkacz made his top 10 debut, becoming only the second Polish man to do so along with clinching the final spot in the ATP Finals, his first qualification for the event.

While his season-ending debut was not ideal, losing all three of his round-robin matches, he still improved his ranking marginally to end the season ranked number nine.

#4 Cameron Norrie

Cameron Norrie at the 2021 BNP Paribas Open.

Cameron Norrie has been grinding it out on the ATP tour for a few years now, making steady progress. 2021 has been the year when he took the next step in his career. He reached three finals this season before winning his maiden title at the Los Cabos Open.

He lost another final at the San Diego Open, but soon won the biggest title of his career at the Indian Wells Masters. While he narrowly missed out on a direct spot in the ATP Finals, he nevertheless got an opportunity to play as an alternate. Norrie is also close to making his top 10 debut, currently ranked at number 12.

#5 Aslan Karatsev

Aslan Karatsev at the 2021 Australian Open.

Aslan Karatsev's breakthrough is one of the feel-good stories of the year. He started the year ranked outside the top 100 and hadn't played in the main draw of a Grand Slam or an ATP 1000 event.

He came through qualifying to make his main-draw Grand Slam debut at the Australian Open. Karatsev made it all the way to the semifinals where he lost to Djokovic. He soon won his maiden title at the ATP 500 in Dubai and at the end of the year, won his second title at the Kremlin Cup, while reaching a career-high ranking of number 15.

Karatsev also did well in doubles, reaching the final of the mixed doubles at Roland Garros and winning the silver medal at the Tokyo Olympics, both with Elena Vesnina.

He also won the doubles title in Doha with Andrey Rublev and reached the final of the Indian Wells Masters. Karatsev's rise to the top is a story of perservering and defying the odds, as many players quit in their late 20s after not finding success but instead he kept on going.

With the tremendous success they've had this year, the men will be eager to build upon it in 2022, and most likely, they will do so.