THROWBACK: Zverev breaks through at 2018 ATP Finals

Long touted as the future of men's tennis, Alexander Zverev lived up to expectations as he capped off an impressive 2018 by winning the season-ending Nitto ATP Finals.

At just 21-years of age, Zverev became the youngest winner of the event since Novak Djokovic triumphed there a decade earlier. The German had qualified for the second consecutive year, and was hoping to better his record of 1-2 in round robin play from the previous year.

After advancing out of the group stage with wins over Marin Cilic and alternate John Isner, Zverev faced Roger Federer in the semifinals. The lanky youngster defeated Federer in two tight sets before clashing with World No.1 Novak Djokovic in the final.

Although Zverev had fallen to Djokovic in the group stage, he pulled off the biggest win of his career by upsetting the Serbian 6-4 6-3 to win the title. This was also his first victory over a current World No.1 on the ATP Tour.

Despite the controversy surrounding Zverev at the moment, he will be competing in this year's event with the hopes of adding a second ATP Finals trophy to his cabinet.

Prior to the Finals in London next week, the Sofia Open is the last tournament of the season. Click here for up-to-date results and live scores.