Watch: Stefanos Tsitsipas returns to training, posts humorous video of new grunts 

World No. 4 Stefanos Tsitsipas has returned to training ahead of the new season and he has made one little tweak to his game -- new grunts.

The Greek posted a video of himself training on Instagram and every time he hits a shot, we can hear him grunting very loudly. Of course, the video is light-hearted and fans might not actually hear Tsitsipas grunting so loudly on court.

The 23-year-old has been very active on social media, tweeting a series of motivational quotes. One such tweet reads:

"There will be many times in your life when you’ll be questioned, undermined, or criticized for your behavior, personality or ideas. Always stand up for being your own self, and don’t feel obligated to explain why you have nurtured the skills you have built over time."

Tsitsipas is well known for tweeting quotes like this. Another tweet from him reads:

"Work until you no longer have to introduce yourself."

Stefanos Tsitsipas will kick off 2022 at the ATP Cup

Tsitsipas will represent Greece in next week's ATP Cup

The 23-year-old had a pretty good 2021 season as he won his first Masters 1000 title at the Monte Carlo Masters, defeating Andrey Rublev in the final. Tsitsipas became the first Greek player to win a Masters 1000 event and achieved this feat without dropping a single set.

He reached his maiden Grand Slam final at the French Open and had a two-set lead over Novak Djokovic before the Serb fought back to defeat him. The Greek also reached the semifinals of the Australian Open, Canadian Open and the Cincinnati Masters. He ended 2021 ranked fourth. This is Tsitsipas's highest year-end ranking.

The 23-year-old starts 2022 at the ATP Cup, which begins on January 1. He will be representing Greece, who are in Group D of the competition, along with Poland, Argentina and Georgia. Tsistipas will have to be at his absolute best if the Greeks are to reach the semifinals of the tournament.

Tsitsipas will go on to participate at the Australian Open, attempting to better his semifinal appearance from last year. Hopes will be high for Tsitsipas at the Asia-Pacific Grand Slam, particularly if Djokovic does not participate in the competition.

After coming close to winning the French Open last year, the Greek will be attempting to win his first Major in 2022 and become the first player from his country to win a Grand Slam.