Defending champion Andy Murray’s chances of retaining his Olympic crown have been boosted after two-time grand slam winner Stan Wawrinka became the latest top-10 ranked player to withdraw.
World No4 Wawrinka has been forced to pull out of the Games, which start on Friday, after succumbing to a back injury which he aggravated during the Rogers Cup in Toronto last week.
The 31-year-old’s absence means five of the world’s top 10 players will not take to the court in Rio de Janeiro. Roger Federer, Tomas Berdych, Milos Raonic and Dominic Thiem had already withdrawn, while Rafael Nadal remains an injury doubt.
“I am very sad,” said Wawrinka. “Going to Rio was close to my heart. After Beijing  and London , I wanted to live these Games in Brazil.
“Sadly, it’s not possible. I wish good luck to all the Swiss athletes who will go to Rio and I will support them from distance.”
Wawrinka is the third Swiss player to withdraw from the Games after Federer was sidelined with a knee injury and Belinda Bencic, who was forced out of Wimbledon at the second round stage with a wrist injury, also dropped out.