World number four Stan Wawrinka withdrew from the Rio Olympics with a back injury on Tuesday, dealing another blow to the tennis tournament which has been hit by a series of high-profile pull-outs.

The 31-year-old is the third Swiss player to withdraw after Roger Federer and Belinda Bencic who also scratched from the event through injury.

"I am very sad," said Wawrinka, the former French and Australian Open champion.

"Going to Rio was close to my heart. After Beijing (2008) and London (2012), 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 aggravated his back injury in Toronto last week where he reached the semifinals.

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