US Open champion Andy Murray has pulled out of the Swiss Indoors in Basle due to a back injury.
The Olympic champion, who was seeded second behind defending champion Roger Federer, withdrew from the event which starts on Monday ahead of a busy schedule at the end of the season.
A statement on the tournament's website, www.swissindoorsbasel.ch, said: "Late on Friday evening, news reached Switzerland from the ATP World Tour's European headquarters in Monaco that Scotland's Andy Murray had been forced to withdraw from the Swiss Indoors Basel due to a back injury."
It is the second successive year that injury has forced Murray to pull out of the tournament.
The 25-year-old requested a wildcard to play in Basle a year ago only to suffer a strained gluteal muscle just before his opener against Robin Haase.
"There is a fine line between good luck and bad luck," said tournament director Roger Brennwald.
Murray will now instead focus on his run to the end of the year starting with the Paris Masters which begins next week.
The Scot will then head to the World Tour Finals in London, which begin on November 5.