STEFANOS TSITSIPAS underlined his status as the future of mens tennis as he became the youngest debutant winner of the ATP Finals for 41 years.
In this prestigious season-ending tournament, the Greek youngster wrote his name alongside illustrious company in the history books with a 6-7 6-2 7-6 victory over Austrian Dominic Thiem.
At the age of 21 years and three months, he is the youngest man since rookie John McEnroe in 1978 to lift the trophy at his first attempt.
And he is the youngest champion since 20-year-old Lleyton Hewitt in 2001.
Tsitsipas, who studies his opponents by watching them play on YouTube, banks his largest cheque of 2.1m just 12 months after he won the Next Gen finals and will now fancy his chances of contesting for the Grand Slams in the New Year.
As he exited the semi-finals on Saturday, Roger Federer warned there could be a changing of the guard in 2020 with his ATP finals conqueror Tsitsipas the likely man to lead the revolution of the Next Generation.
Incredibly, this was the first major tournament since the 2010 Miami Open where the Big Three of Federer, Nadal and Novak Djokovic had all been knocked out in the semi-finals or earlier. Essentially when the three titans have all been involved in the same draw, at least one of them reaches the final.
In the first set here, there was little to choose between the two players, who unhelpfully both wore orange head and wristbands, grey shirts and white shorts.
For those up in the Gods of the O2 Arena it was hard to work out which player was which especially as they both have the best one-handed backhands in the business and their stats were almost identical as the match went to a tie-breaker.
In the decisive moments, it was the older man Thiem who had the experience and greater guile to take the advantage on his second set point, smashing down an impressive serve to seal the set.
Tsitsipas, however, did not let that disappointment affect his tennis and thanks to the benefit of a double break meant he raced in to a 4-0 and then 5-1 lead before securing the second set in the space of 26 minutes.
In the deciding set, Tsitsipas enjoyed an early break to go 2-1 ahead but Thiem finally broke back to go to 3-3.
Thiem, 26, appeared to have the momentum going into the final tie-break but Tsitsipas held his nerve to achieve the biggest piece of silverware in his burgeoning career.
