Maria Sharapova and Samantha Stosur have played each other 15 times, and Sharapova has won 13 of those matches. Stosur's two wins came on hard courts, while Sharapova has won all three of their clay court matches. Should Sharapova prevail again tomorrow, she'll face either Garbine Muguruza or wild card Pauline Parmentier in the quarterfinals. Logic tells us that she'll face Muguruza, which might be interesting.
Muguruza, in my opinion, is technically more vulnerable to a Jankovic- or Halep-type player than she is to a Sharapova, in that those players would instinctively know how to move her around and expose her vulnerability. Having said that, I should add that for the Spaniard to beat Sharapova, she would have to play the same kind of "first strike over and over" game that she played against Serena Williams. As Vika might say, "good luck with that." All the same, an interesting proposition. Muguruza gets a shot at pressuring Sharapova to go for too much on her second serve and double-fault, though that hasn't stopped the Russian from winning before.
Angelique Kerber and Genie Bouchard have played each other only once, it was on a hard court, and Kerber won in three sets. The German says that her back injury has completely healed. If that's the case, she'll be quite a challenge for the young Canadian.
Probably the most interesting of the matches to be played tomorrow is the one that features Ajla Tomljanovic and Carla Suarez Navarro. Suarez Navarro has a history of serious choking, but she recently, finally, won her first tour title. On the other hand, this is a major, and there could be some regression. Tomljanovic has faced her demons at this tournament, and seems the more relaxed for it. At any rate--unless something goes really wrong--this has the potential to really be a match worth watching.
The round of 16 matches created by today's play are pretty interesting, too. A resurgent (for now) Svetlana Kuznetsova made her way past Petra Kvitova (I got to see only some of this completely frustrating yet exciting match, but Todd has written a detailed description of it), who had the match on her racket and let it go. It probably could have been called the Battle of the Talented Head Cases.
Anyway, Kuznetsova will play Lucie Safarova in the next round, and since both are so good on clay, the match should be a spectator's delight. Jelena Jankovic will play Sara Errani, and that promises to be a battle. Qualifier Kiki Bertens, who has emerged more or less out of nowhere, gets Andrea Petkovic. Petkovic is certainly favored to win, but the way things are going, we can't count on anything.
Finally, Sloane Stephens will play 4th seed Simona Halep, who has lost only eleven games so far. Stephens is 2-1 against Halep, but Halep won their only match on clay, which was in 2012, before the Romanian became the force that she is today.
When the tournament began, there were five former champions competing. Now there are two--Sharapova and Kuznetsova. There are also two former finalists, Stosur and Errani, who are still in the draw.
For a detailed list of interesting French Open stats, see WTA Backspin.