Novak Djokovic voices Olympics Zika concern after Day, McIlroy withdrawals

If an "uncertain" Jordan Spieth or any other golfers are looking at tennis before deciding whether to compete at the Olympics, they may well give Rio de Janeiro a miss.

Jason Day and Rory McIlroy are among the golfers to have already withdrawn from the Olympic tournament, citing the fear of contracting the Zika virus.

Many tennis players' enthusiasm for the Olympics appears to have softened, too, although in most cases, that has little or nothing to do with health risks.

"I've been trying to reach out to Brazilian friends and acquaintances, [to] get information ... When I get more, I'll be able to make my final decision." Novak Djokovic

The changing mood in a more established, albeit relatively-recently-added, Games discipline could be another negative influence on the thinking of golfers who are deliberating whether to travel or not.

It has often been said that golf, which is new to the Games this year, should be guided by tennis on how a sport can prosper inside the Olympic movement.

After all, there are great similarities between tennis and golf -- both are individual sports, with global tours, and four traditional peaks each season in the majors.

The parallels between the sports have been acknowledged by key figures within the Olympic movement; Antony Scanlon, the International Golf Federation's Olympics head, even told ESPN last February that "for our athletes it will be less of a journey than it has been for tennis".

But, if you look beyond some of the leading tennis players, there doesn't appear to be the same commitment to the Olympics that there was four years ago in London, when Andy Murray won the men's singles gold medal.

It's true that Murray will be motivated to defend his title, while Roger Federer will want the only big singles prize missing from his collection of titles.

Novak Djokovic, meanwhile, has the opportunity this season of becoming the first man to accomplish the golden slam -- winning the four Grand Slams and the Olympic in the same year.

He is understandably keen to play in Rio, and hasn't been shy about saying so. He's officially on the Serbia team, too, but the world No.1 told a media conference at Wimbledon this week that even he is concerned about Zika.

"I've been getting more and more information about it," he said. "Last few days I've been trying to reach out to as many Brazilian friends and acquaintances that I have, [to] get as much information [as possible].

"When I get more information, I'll be able to make my final decision. But for now, I'm planning to go."

For some of the other players, even for those who would have had an outside chance of winning a medal, the Olympics simply aren't a priority.

One of the most engaging storylines this tennis season has been the emergence of Dominic Thiem, who is the newest member of the top 10, and yet the 22-year-old Austrian won't be in Rio as he doesn't consider tennis to be a true Olympic sport.

Ernests Gulbis, a former French Open semifinalist, seems to be thinking along similar lines, with the Latvian saying recently that the Olympics looked like "tennis tourism".

He is ineligible after playing insufficient Davis Cup matches, but was unhappy anyway that ranking points wouldn't be on offer in Rio, as they were in London.

John Isner, of the United States, also won't play in Rio and has expressed a similar grievance. "The fact that they have no points, to be honest, was a pretty big factor," he said. "Obviously the Olympics is not about the money, but no points I think hindered me a bit."

The lure of a medal just isn't enough to get some to Brazil and while no-one is stressing the lack of a financial incentive, that could be a factor.

Australian Bernard Tomic will be playing at an ATP event in Mexico rather than the Games. In a statement, he cited his "extremely busy playing schedule, and now my personal circumstances" for his absence.

Another young Australian, Nick Kyrgios, will be missing from Rio after falling out with the Australian Olympic Committee. While Kyrgios said that playing at the Olympics "had been a dream since I was a kid", he wasn't making himself available after the committee "chose to publicly and privately disparage" him.

South Africa's Kevin Anderson and Spain's Feliciano Lopez also won't be there. The tennis tournament in Rio has been described in some quarters as "the fifth Grand Slam", but for a number of tennis players, that appears to be anything but the case.