Juan Martin del Potro put six straight defeats to Roger Federer behind him to beat the Swiss tennis star in his home event, the Swiss Indoors tournament in Basel.
Two of the three sets went to tiebreaks with the towering Argentinian eventually winning 6-4 6-7 7-6 to claim his second title in as many weeks following his win in Vienna.
The two were meeting for the first time since their epic Olympic Games semi-final when Federer eventually won in a 36-game final set.
Both Federer and Del Potro - who qualified by reaching the quarter-finals in Basle - are assured of their place in the season ending ATP Finals in London in a week.
Two of the eight places remain up for grabs.
The final qualifying event, the Paris Masters, starts tonight.