Stanislas Wawrinka's Masters Cup hopes have suffered a major setback after losing his first round match in the Swiss Indoors tennis tournament.
German qualifier Benjamin Becker, ranked 137th, defeated the Swiss men's number two by 3-6, 7-6 (5), 7-6 (5) in Monday's match in Basel.
Although Wawrinka led at times, serving up two match points, Becker battled through two tie-breaks to take control of the final sets.
Wawrinka will need an exceptional performance in next week's Paris-Bercy tournament to have a hope of reaching the Masters Cup in Shanghai in November. The 23-year-old is 11th in the ATP standings, and only the top eight qualify.
Two-time defending champion Roger Federer will open play on Tuesday against 86th ranked Bobby Reynolds of the United States.
The tournament is the world's third largest indoor event and runs until October 26.