Naomi Osaka may have lost in women's singles, but there are still major contenders in the tennis competitions at the 2020 Tokyo Olympics. Here are highlights from day four of the tournament. 

Naomi Osaka handles Viktorija Golubic in Round 1 of women's singles at the 2020 Tokyo Olympic Games.

NBC Olympics

World No. 2 Naomi Osaka was booted from singles competition in a straight sets, third round loss to the Czech Republic's Marketa Vondrousova, 6-1, 6-4. The four-time Grand Slam champ and fan favorite -- who lit the Olympic cauldron at the opening ceremony just days earlier -- played loose and dropped the first set in less than half an hour. The remaining women's singles competition is now wide open, with no clear leader. There's at least one Slam winner still in play: Spain's Garbine Muguruza. 

Men's doubles team Austin Krajicek and Tennys Sandgren won their second round match, 6-7, 6-2, 10-5, on Tuesday, along with women's doubles team Bethanie Mattek-Sands and Jessica Pegula, who swept France in their second round match, 6-1, 6-4. Mattek-Sands previously won mixed doubles gold at the 2016 Rio Olympics.

It wasn't all good news for American doubles teams, though, as the other men's doubles team of Rajeev Ram and Frances Tiafoe fell to Croatia in straight sets, 6-3, 7-5.

Andy Murray, Great Britain's two-time Olympics singles gold medalist (and a London 2012 silver medalist in mixed doubles), seeks the only Olympic achievement that's eluded him thus far: a men's doubles medal. He took one step closer towards that goal today with a victory over Germany alongside compatriot Joe Salisbury, 6-2, 7-6. 

Murray has struggled with a variety of injuries since his last Olympics appearance, especially hip problems. But recent surgeries may lead to a resurgence.  

Men's singles:

ARG's Diego Schwarzman def. CZE's Tomas Machac, 6-4, 7-5

JPN's Kei Nishikori def. USA's Marcos Giron 7-6, 3-6, 6-1

GBR's Liam Broady def. POL's Hubert Hurkacz 7-5, 3-6, 6-3

Women's singles:

UKR's Elina Svitolina def. GRE's Maria Sakkari, 5-7, 6-3, 6-4

ESP's Garbine Muguruza def. BEL's Alison Uytvanck, 6-4, 6-1