Swiss Indoors: Roger Federer beats Juan Martin del Potro to win eighth Basel title
Switzerland's Roger Federer beat Argentine Juan Martin del Potro to win the Swiss Indoors - then withdrew from next week's Paris Masters.
Federer's 6-7 (5-7) 6-4 6-3 win moved him within 1,460 points of Spanish world number one Rafael Nadal before the final regular-season event.
But the 36-year-old will not play in Paris, all but ending his chances of ending the year top of the rankings.
Federer, an eight-time winner in Basel, has won seven titles in 2017.
Victory for Del Potro would have moved him into the final qualifying place for the ATP finals in London.
Having won in Stockholm last week, the world number 19 was targeting back-to-back titles in Basel but the 29-year-old remains one place behind Spain's Pablo Carreno Busta.
Del Potro must reach at least the semi-finals in Paris to claim the final spot.
"It's unbelievable how well Roger is playing," said Del Potro. "I hope to be in such shape when I'm his age. But I doubt I will be."
In Vienna, Frenchman Lucas Pouille secured a comfortable 6-1 6-4 victory over compatriot Jo Wilfried-Tsonga to claim his third title of the season.
Tsonga, another contender for the finals in London, is now 295 points behind Carreno Busta with the two remaining places to be decided in the Paris.
Federer shows frustration
Federer and Del Potro had met on four previous occasions in 2017, with the latter winning their last meeting - a US Open quarter-final last month.
In a tight opening set, Federer had the chance to take it on serve, only for Del Potro to break, and the Swiss player then lost five points in a row to surrender the tie-break.
Federer's frustrations came to a head in the fourth game of the second set when he blew the chance to stamp his authority back on the match.
The 19-time Grand Slam champion carved out a break point and took control of the rally at 30-40, only to send a simple backhand volley wide.
It triggered an angry outburst as Federer smashed his racquet into the net in a rare show of emotion.
However, he regained his composure to break in the final game of the set, before wrapping up the victory with two further breaks in the third.
Federer now has 95 career titles, with American Jimmy Connors leading the all-time list on 109.