Andy Murray marked reaching world number for the first time by defeating John Isner to claim his maiden Paris Masters title.
The newly installed king of men's tennis prevailed 6-3 6-7 6-4 to claim a career-best eighth title of 2016 to deny his American opponent a first Masters Series title at the third attempt.
The 29-year-old Murray was already assured of replacing Novak Djokovic at the top of the ATP rankings after Milos Raonic withdrew from the pairs semi-final clash through injury, but victory in the French capital cements his status as the man of the moment in the men's game.
Victory also boosts Murray's task of ending the season as the year-end world number one and he heads to the ATP World Tour Finals as the man to beat at the O2 Arena.
The Wimbledon and Olympic champion will start the season-ending tour finals 405 points ahead of Djokovic ahead of a potential straight shoot-out to end the year at the summit of the standings.
"This has been an incredible journey for meet get to the top of the rankings I couldn't have done it without all of you [friends and family]," Murray said. "Thanks to them for all their hard work, they make a lot of sacrifices to allow me to compete and travel the world. I'll keep working as hard as I can to keep getting better. I must congratulate John on a great week. He played unbelievable tennis today. We played last week [in Vienna] and the difference was huge so congratulations to his team."
Murray heads to the English capital off the back of 19 straight wins and four tournament victories in his last five events, though he was pushed all the way by US number one Isner.
The Brit took the opening set after some wayward Isner volleys but a tiebreak in the second set saw the match squared.
Isner's unerring consistency on serve was threatening to upset Murray's crowning as world number one but a pair of virtuoso backhands secured victory in three sets.
A win by any method at the ATP Finals will be enough to keep Murray at the top of the rankings heading into the Australian Open in 2017, while Djokovic must win a fifth straight title with two round robin wins to stand any chance of returning to the summit.