Kyrgios has only played one competitive match since autumn 2022, when he has been suffering from a knee injury.
My body is finally ready to step out onto the court again and have fun. It's been a long time, says Kyrgios
"NK" has previously said that his career may be over, but is now making himself ready to play again.
The Australian is entering the quarterfinals in UTS, where he will face Norwegian Casper Ruud.
The concept of UTS was founded in 2020 by tennis coach Patrick Mouratoglou, who wanted to create a more modern, faster tennis with more emotions and excitement.
Other participants in this year's edition include Alex de Minaur, Stefanos Tsitsipas, Andrej Rublev, and Gaël Monfils.
Kyrgios has been ranked as high as 13th on the world ranking, and has made himself known for being outspoken and showing emotions on the court.
The match between Kyrgios and Ruud will be played on August 22. A few days later, the US Open will begin.