RIO: Novak Djokovic, Andy Murray, Rafael Nadal and Serena Williams will display their Grand Slam talents in Rio, but with serious questions being asked over tennis's place in the Olympics after a host of high-profile pull-outs.

Colourful Latvian player Ernests Gulbis dismissed the tournament as “tennis tourism”, angry over the absence of prize money and ranking points.

Others have withdrawn due to injury – most notably 17-time major champion Roger Federer – scheduling fears and worries over the Zika virus.

The absentees represent the latest chapter in the sport's on-off relationship with the Olympics.

From 1924 until 1988, tennis disappeared from the schedule in a dispute over the place of professionals in what was seen as an amateur showpiece.

This time, the men's event will be missing top 20 players Federer, Milos Raonic, Tomas Berdych, Dominic Thiem, Richard Gasquet, John Isner, Feliciano Lopez and Nick Kyrgios.

The women's singles are stripped of Simona Halep, Victoria Azarenka, who is pregnant, Belinda Bencic and Karolina Pliskova.

Maria Sharapova, silver medallist behind Serena Williams at the 2012 London Olympics, is serving a two-year doping ban.

The men's doubles suffered a body blow when defending champions Bob and Mike Bryan opted out, insisting “our family's health is now our top priority”.

World number one Djokovic said he has no fears about playing in Rio where he seeks a first Olympic gold medal to add to the career Grand Slam of the four majors he completed at the French Open in June.

“Of course there is always a possibility that you can get that virus, but I think maybe the fuss has been created with some kind of other intent. But I'm not going to get into that,” said the 29-year-old Serb who warmed up for the Games by claiming a 30th Masters title in Toronto on Sunday.

Djokovic hinted at what many in sport feel – that Zika is a convenient cover story for players who are concerned over the lack of ranking points at an event which also cuts into schedules geared specifically towards the US Open, the season's final major, in New York just one week after the Games conclude.

World number two Murray also has no reservations about Rio where he will defend the career-changing gold medal he won at the 2012 Games at Wimbledon.

Murray has not played since his lifting his second Wimbledon title three weeks ago.

The 29-year-old, who also won a silver medal with Laura Robson in the mixed doubles in London, instead headed to Spain to practice with Nadal, the 2008 Olympic champion.

Hingis gets place

Nadal, meanwhile, is desperate to play in Rio having been forced to skip the London Games with a knee injury.

However, the 14-time Grand Slam champion is battling to recover from a wrist injury which has kept him off the tour since an early French Open withdrawal.

Having equalled Steffi Graf's Open era record of 22 Grand Slam singles titles with a seventh Wimbledon crown, Serena Williams will be playing in her fourth Olympics.

The 34-year-old world number one won singles and doubles gold – with sister Venus – in London to add to her doubles titles in Sydney in 2000 and Beijing eight years later.

By winning the 2012 title, the American star became the fourth player after Andre Agassi, Nadal and Graf to complete the Golden Slam of the four majors plus Olympic gold.

The decision of Federer to call time on his season to recover from a knee injury had the knock-on effect of putting Swiss compatriot Martina Hingis's Games in peril.

The five-time Grand Slam singles champion last played in the Olympics at Atlanta in 1996 and had been due to play women's doubles with Bencic and mixed with Federer.

But she will now play doubles with Timea Bacsinszky after replacing Viktorija Golubic.

The tennis tournament runs from August 6 until 14 at the Barra Olympic Park where the main court, named after Brazilian tennis veteran Maria Bueno, holds 10,000 fans.

Five golds are up for grabs – men's and women's singles and doubles and mixed doubles.