The biggest names aren't avoiding Rio because of the Zika virus -- unlike in golf -- but rather injuries.
After two-time grand slam champion Stan Wawrinka announced he will miss the Games due to a back problem Tuesday, it leaves just five of the world's top 10 men competing for the gold medal in Rio.
Wawrinka is the third Swiss player to bail from the Olympics, after Roger Federer and Belinda Bencic also succumbed to injuries.
"I'm very sad," Wawrinka, who won gold with Federer in doubles in 2008, said in a statement. "I was really excited about playing in Rio."
Federer misses the opportunity to add a singles gold medal to his already overflowing trophy cabinet after pulling out of the Games -- and the rest of the season -- through a knee injury.
Besides the singles, he had been expected to partner five-time grand slam singles winner Martina Hingis in Brazil, in a collaboration that got tennis fans into a frenzy.
Federer's absence means world No. 1 Novak Djokovic is the clear favorite for the gold medal, with reigning Olympic champion Andy Murray right behind him.
Novak Djokovic's year for gold?
Djokovic will go down as one of tennis' greats and has won almost everything on offer, but an Olympic title still eludes him.
By claiming June's French Open -- the one major the Serb had previously failed to win -- Djokovic became just the eighth man to capture all four grand slams.
The most dominant player of the last two years, this may the Serb's best -- and last realistic -- chance to win gold since he will be 33 in Tokyo come 2020.
Djokovic's unexpected reverse to Sam Querrey in the third round at Wimbledon in a sloppy, unfocused outing -- after he swept to a fourth straight major in Paris -- is sure to make onlookers wonder if the world No. 1 is set for a mild slump.
However, Djokovic travels to Rio having won the Rogers Cup in Toronto and his Wimbledon defeat could give more motivation to the Serb, who has spoken in the past about the importance of the Olympics. The surface of the Olympic tournament, hard court, is Djokovic's most successful.
Questions also surround two of his fellow members of the "Big Four," Nadal and Murray, who have each won an Olympic gold medal in singles.
Nadal, the 14-time grand slam winner, hasn't played since the first week of the French Open. He pulled out of Roland Garros with a left wrist injury and then withdrew from the Rogers Cup, which means the 2008 singles champion didn't participate in any tournaments ahead of Rio.
Out of the 2012 Games with a knee injury -- when he was due to be Spain's flag bearer -- Nadal has made little secret of how desperate he is to participate at a third Olympics.
How much will Murray have left, emotionally and physically, in the wake of an already long season that saw the Scot win a second Wimbledon title in early July? He skipped the Rogers Cup to recover, mentally, from Wimbledon.
The Williams sisters, Venus and Serena, won't be the lone siblings to pair up in Rio, as Murray and older brother Jamie are one of the medal favorites in men's doubles.
The ever present Venus Williams
Venus reiterated how much the Olympics meant to her at the French Open.
"The proudest moment for me when they do the on-court announcements are the Olympic results," she told reporters, referring to emcees introducing players prior to matches. "For me that feels legitimate."
The 36-year-old is set to play in a fifth Olympics -- and she has only failed to win a medal at one, in 2004. Venus and Serena Williams, the two-time defending champions in women's doubles, geared up for Rio by winning the doubles crown at Wimbledon.
In 2004, the sisters were foiled by injury: They didn't play together because of a knee injury to Serena.
But should Venus be discounted from the singles? Her showing at Wimbledon suggests not. The seven-time grand slam winner, slowed by the autoimmune disorder Sjogren's Syndrome, received a significant boost by landing in a first grand slam semifinal since 2010
Two men's players in their 40s, both now doubles specialists, are trumping Venus Williams in Olympic appearances.
India's Leander Paes -- a bronze medalist in singles in Atlanta in 1996 -- readies for No. 7 and Canada's Daniel Nestor -- a gold medalist in doubles in 2000 who got in this year when countryman Milos Raonic withdrew from Rio -- competes in a sixth.
Maria Sharapova and the others missing
Raonic, the Wimbledon finalist, announced in July he wouldn't be making the trip, with Zika one of the reasons listed. Later, however, he implied to media in Canada that he wanted to focus on the U.S. Open and that meant sticking to his usual routine of playing at the Rogers Cup and then in Cincinnati.
Tomas Berdych, the 2010 Wimbledon finalist, and 2014 French Open finalist Simona Halep are bypassing Rio because of the threat of contracting the mosquito-borne virus.
The flurry of Zika-led withdrawals led to criticism from Brazilian doubles star Bruno Soares.
Maria Sharapova, the richest female athlete of the last decade, is serving a two-year suspension for doping. Twice grand slam winner Victoria Azarenka, meanwhile, is pregnant.
Others, including French Open semifinalist Dominic Thiem and American No. 1 John Isner, have elected to focus on hard-court tournaments in North America.
Then there is the controversial Nick Kyrgios, who announced in June he wouldn't be playing after his behavior was criticized by his country's Olympic chef de mission, Kitty Chiller.