Italian wildcard Jannik Sinner has won the Next Gen ATP Finals after beating Australia's world number 18 and top seed Alex de Minaur 4-2 4-1 4-2.
De Minaur also lost of the final last year, at a tournament that is for the best players aged 21 and under.
Sinner, 18, is the youngest player inside the world's top 100 - at 95 - after jumping more than 450 places in the rankings this year.
"The week has been unbelievable," said Sinner, the tournament's third winner.
Playing in front of a home crowd in Milan, he added: "I wouldn't be here without the wildcard, so thanks to everyone. I hope to be back here next year."
The previous two champions, South Korean Chung Hyeon (2017) and Greece's Stefanos Tsitsipas (2018), both reached the Australian Open semi-finals two months after winning the title.
Sinner, who was a champion skier, but chose tennis aged 13, reached the US Open first round in August.