The Rio Olympics were hit with yet another heavy blow three days before the opening ceremony, as world No 4 Stanislas Wawrinka decided to pull out of the event because of a back injury. This means that almost half of the world's top 10 men's singles players will be missing from action in Rio. Earlier, Roger Federer, Tomas Berdych, Milos Raonic and Dominic Thiem had also pulled out citing various reasons.

A statement issued by Wawrinka's management company read, "Stan Wawrinka felt increasing pain during the [Rogers Cup] tournament in Toronto and therefore travelled back to Switzerland in order to consult with his doctor for a complete check-up. Following analyses and a MRI scan, local overstress was discovered and he was advised to reduce his physical activity for an undetermined period during which he will undergo further examinations."

The deadly Zika virus has been a major deciding factor in players taking the flight to Rio or not. Switzerland, who looked certain to win a medal in the build-up to the event are now without their top two stars in Federer and Wawrinka. There are also doubts over the fitness of the 2008 Olympics men's singles gold medal winner, Rafael Nadal. However, the Spaniard has shown plenty of determination to shrug off his fitness worries and participate in the event. The Byan brothers – Bob and Mike – also withdrew from the tournament a few days ago, citing concerns over Zika, and will not defend their gold medal in the men's doubles category.