US Open champion Andy Murray has withdrawn from the Swiss Indoors event starting on Monday because of injury.
The 25-year-old Scot, who lost to Novak Djokovic in the Shanghai Masters final last weekend, is resting his back ahead of a busy end-of-season schedule.
He plays in the Paris Masters beginning on 29 October and the World Tour Finals in London, which start on 5 November.
World number one Roger Federer defends the Swiss title and begins against Frenchman Jeremy Chardy on Monday.
Federer has won the tournament in five of the last six seasons.
Murray, however, who also pulled out of the Basel event last year, has not played a match at the St Jakobshalle venue since his only appearance in 2005.
World number two Djokovic is also absent this week so Argentine Juan Martin del Potro, seeking to secure a place in the World Tour Finals, takes the second seeding, ahead of Richard Gasquet of France.
Swiss Stanislas Wawrinka is seeded fourth and begins against Russian veteran Nikolay Davydenko.