World number four Stan Wawrinka has become the latest high-profile player to pull out of the Olympic tennis event.

The Swiss star, who is reportedly struggling with a back injury, joins compatriot Roger Federer in withdrawing in another blow to the tournament.

A statement issued by Wawrinka’s management company said: “After a medical examination by his doctor in Geneva, the current world number four has to withdraw from the Olympic Games which will start in Rio this week.

“Stan Wawrinka felt increasing pain during the tournament in Toronto. 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.”

Switzerland had harboured hopes of medal success in singles and doubles, with Federer planning to partner Martina Hingis in the mixed doubles.

But the 17-time grand slam champion brought an early end to his season last week in order to recover fully from knee surgery in February and now Wawrinka has joined him on the sidelines.

Wawrinka and Federer won gold in the men’s doubles in 2008 with Federer taking silver in the singles four years later in London.

Notable absentees

Half of the men’s top 10 will be absent from Rio, with Tomas Berdych and Milos Raonic withdrawing because of fears over the Zika virus and Dominic Thiem also choosing to skip the event.

There are also question marks over Rafael Nadal’s fitness following a wrist injury.

The 2008 gold medallist withdrew from the French Open with a wrist injury and missed Wimbledon.

“I will not be at the best level in any of the categories,” Nadal told journalists after arriving in Rio.

“I have not competed for two months and I have not trained a lot.”

“I will train a few days here to see what I can do and then decide what is best, to be more positive for me and the team,” he added.