World tennis number three Andy Murray has dropped out of the Swiss Indoors tournament in Basel because of muscle strain.
Roger Federer, on the other hand, has won through to the quarterfinals, although he dropped a set against Jarkko Nieminen of Finland.
Murray announced his decision not to play only 75 minutes before his scheduled match on Wednesday afternoon against Robin Haase of the Netherlands was due to start.
Murray, who took over the third ranking from Federer in October, is just 95 points ahead of the Swiss star. He had wanted to play in Basel in order to avoid being penalised by the ATP, whose points determine the rankings.
His place reverted to Swiss player Marco Chiudinelli, who then lost 2-6, 6-7 to Haase.
Haase meets another Swiss, Stanislas Wawrinka, in the next round.
The Swiss qualifier Michael Lammer lost in three sets to Marcos Baghdatis of Cyprus.
In compliance with the JTI standards