Bulgaria's Grigor Dimitrov became the first man for 19 years to win the ATP Finals on his debut appearance with victory over Belgian David Goffin.
Sixth seed Dimitrov, 26, claimed the biggest title of his career as he won 7-5 4-6 6-3 at London's O2 Arena on Sunday, the BBC reports.
The Bulgarian collected £1.9 million in prize money for coming through the tournament unbeaten in five matches across the group stage, semi-finals and final.
He will end the year ranked third in the world, with Goffin up to seventh.
"I'm still trying to think about what I just did," said Dimitrov, who follows in the footsteps of Spain's Alex Corretja, who won the season-ending title on his debut in 1998.
"This is a great, unbelievable achievement for me, but I still have a lot to give."
"One of my main goals is to win a Grand Slam tournament. This has always been a dream of mine. Now, slowly, I think [I'm] getting there."
Injuries to Andy Murray and Novak Djokovic kept two of the sport's biggest names out of the ATP Finals, while world number one Rafael Nadal was forced to pull out injured after his opening round-robin match and Roger Federer was stunned in the semi-finals by Goffin.
But Dimitrov said it was too soon to say a new era was coming to tennis.