Tennis superstar Serena Williams is sympathetic to Jason Day’s withdrawal from the Rio Olympics over Zika virus concerns.

But the world No.1 won’t follow suit, saying the Olympics have provided some of her favourite memories – including the singles gold medal she won at London in 2012.

Day, golf’s world No.1, on Tuesday joined fellow Australians Adam Scott and Marc Leishman, as well as high-profile stars Rory McIlroy, Vijay Singh and Louis Oosthuizen, in avoiding the Rio Games.

In tennis, several of the game’s biggest names – including Australian pair Nick Kyrgios and Bernard Tomic – have pulled out for varying reasons.

Top-25 players Dominic Thiem, Feliciano Lopez, John Isner and Kevin Anderson have also indicated they won’t compete in Rio.

World No.5 Simona Halep is believed to be the only leading women so far to have expressed doubt about her participation amid concerns over the Zika virus.

Day said the tough decision was purely down to concerns over the mosquito-borne virus, which is being linked to severe birth defects and possible neurological problems in adults.

And Williams sympathised.

“I think it is sad (for people to miss out on the Olympics). But at the same time I obviously understand where they’re coming from and how they feel,” the four-time gold medal winner said.

“Part of me feels that way, too, which is why I’m going in with a whole mindset of how do I protect myself, how do I prevent and also raise awareness for this.

“That’s kind of how I’m looking at it.”

Roger Federer has an individual silver medal and a doubles gold from his Olympic experience, to go with 17 grand slams, and this week remained adamant that he would endeavour to compete in Rio.

“Athletes who have decided not to participate have made a personal decision, but I have never reconsidered my decision,” said Federer, who insisted he would take full precautions against.

“I will try everything I possibly can to be there. For me, it’s always been a big deal – the Olympics.”

Williams added singles gold at the London Games in 2012 to her doubles triumphs in Sydney, Beijing and London.

And it is clear how important competing at the Olympics means to her.

“My experience has been really amazing at the Olympics,” the American said.

“I really loved going out there and competing, really just standing out there and being an Olympic athlete.

“It is really one of the best experiences that I’ve ever had.

“It’s difficult for someone that’s in a sport like golf because their main goal, like tennis, is to win slams.

“For me, I look at the Olympics as a bonus opportunity.

“(Winning gold medals is) not something I’ve dreamt of like other athletes.

“It’s probably one thing I have that I love the most.”