World number one Rafael Nadal has pulled out of next week's Swiss Indoors tournament in Basle citing fatigue.
The Spaniard's success since returning from seven months out with knee problems in February has meant a gruelling schedule.
Nadal has always found hard courts the toughest surface on his body and back-to-back tournaments in Beijing and Shanghai appear to have taken their toll.
The 27-year-old reached the final in Beijing before losing to Novak Djokovic - a result that was nevertheless enough to take him above the Serbian in the rankings - and was then beaten by Juan Martin del Potro in the Shanghai semi-finals.
Nadal wrote on his Facebook page: "Hi all, sorry to announce that I won't travel to Basel in Switzerland but after very exhausting weeks I have to regroup my fitness and my body. I will do my best to come back to the Swiss Indoors next year."
It is a blow to the tournament, whose field also includes Roger Federer, Tomas Berdych, Del Potro and Stanislas Wawrinka.
Nadal had been due to play in Basle, where he has never won a match, for the first time since 2004.
The Spaniard's next tournament is therefore scheduled to be the Paris Masters the following week, which leads straight into the Barclays ATP World Tour Finals in London.