American Jack Sock battled back from a set down to beat qualifier Filip Krajinovic 5-7, 6-4, 6-1 and win the Paris Masters title on Sunday, snatching a place at the World Tour Finals.
The 16th seed ended his Serbian opponent's fairytale run in the French capital to break into the world's top 10 for the first time and take the last place for London from Spaniard Pablo Carreno Busta.
Despite dropping a tight opening set, the 25-year-old upped his game and stormed through the decider to claim the biggest title of his career.
"Incredible week. Hard to describe honestly. I don't think it's really hit or soaked in yet," Sock, who trailed 5-1 in the third set of his opener against Briton Kyle Edmund, told a press conference.
Sock, who was 24th in the 'Race to London' standings before arriving at Bercy, will become the American number one for the first time, after beating the man who knocked out his compatriots Sam Querrey and John Isner earlier in the week.
Jack Sock has the potential to play spoiler in London. He and several young players such as Alexander Zverev and Dominic Thiem round out an impressive field of players at The O2 Arena. The Paris Masters title is exactly what a young up and comer like Sock needs going into one of the biggest tournaments of his career. Sock, just 25-years-old, will look to take on the best in men’s singles tennis next week.
Sock will move into the world's top 10 for the first time when the new rankings are released on Monday, two days before the draw for the ATP Tour Finals, which take place in London from 12-19 November.
