Two former French Open champions still standing as 3rd round is completed

.@K_Siniakova takes the battle of No. 1s!

The top-ranked doubles player takes out singles World No. 1 Osaka, 6-4, 6-2 in the @rolandgarros third round--> https://t.co/JXPNdQQE1D pic.twitter.com/BtiFgjbyei

— WTA (@WTA) June 1, 2019

Five former champions entered the 2019 French Open, but--as of today--only two remain. Those two are 2018 champion (and 2017 runner-up) Simona Halep, and 2016 champion Garbine Muguruza.

Before today, 2009 champion Svetlana Kuznetsova and 2017 champion Alona Ostapenko had already been eliminated from competition. Today, it was Serena Williams, who won the event in 2002, 2013 and 2015. Williams was defeated in straight sets by countrywoman Sonya Kenin, who--though unpolished--clearly has the ability to pull off this kind of upset.

But three-time champion Williams wasn't the only one to make an exit today. Katerina Siniakova took out world number 1 Naomi Osaka in straight sets. Siniakova's doubles career isn't going too well this season (despite the fact that she's part of the world number 1 team), but her singles career got a big pick-me-up today in Paris.

Here is the round of 16 draw:

Katerina Siniakova vs. Madison Keys (14): Keys had to fight to get past her third round opponent, and she'll have to fight to get past Siniakova. Skills-wise, Keys has everything it takes to advance to the quarterfinals, but if she gets into one of her inconsistent patches, Siniakova won't be shy about exploiting it.

Sonya Kenin vs. Ash Barty (8): Can Kenin pull off another huge upset? Barty, who has turned out to be somewhat of a revelation on clay (is there anything the Australian can't do?) will be a very tough customer for her.

Simona Halep (3) vs. Iga Swiatek: The defending champion probably never thought that Swiatek would be her opponent during the business end of the tournament. However, the young (she became 18 yesterday) Polish player won the girls' singles title last year at Wimbledon and the girls' doubles title at the French Open, also last year.  She's played in seven ITF finals and has won all of them. She is, in other words, quite the competitor. My best guess is that she won't be too rattled by having to play Halep in the fourth round, and that she'll make an impression on fans.

Amanda Anisimova vs. Aliona Bolsova (Q): This should be good. Bolsova has already knocked out the likes of Timea Babos, Sorana Cirstea andVera Zvonareva. 17-year-old Anisimova, for her part, has defeated 11th seed Arnya Sabalenka and Irina-Camelia Begu. If there's a "popcorn match," this may be it.

Sloane Stephens (7) vs. Garbine Muguruza (19): This is the match to watch--the former champion vs. last year's runner-up. One never knows what to expect from Stephens, but--so far--her casual elegance on the tennis court has paid off in Paris. They are both such smooth hitters, and when they're at their best, they both make it look so easy. They have played each other only twice, both times were on hard courts, and they are 1-1 against each other. Muguruza is even more mercurial than Stephens, so--in my opinion--it doesn't do much good to try to figure out what will happen.

Donna Vekic (23) vs. Jo Konta (26): Konta has been a total surprise on clay this season; Vekic, not so much. Vekic--who has finally begun to lean into her considerable potential--has already defeated 15th seed Belinda Bencic.

Marketa Vondrousova vs. Anastaija Sevastova (12): When Sevastova has her head about her, she's tough to beat on clay. Assuming she continues to have her head about her, it will be hard for the young Czech to get past her. Vondrousova, however, is pretty clever in her own right.

Kaia Kanepi vs. Petra Martic (31): Kanepi can into a zone and use her big hitting to upset a lot of higher-ranked players, but Martic is very much at home on a clay court and is likely to be too much for Kanepi to handle.