Yastremska outlasts Williams in closest match of the day
The 20-year old Ukrainian needed two hours, 35 minutes to slip past Venus Williams 5-7, 6-2, 7-5. Yastremska jumped out to a 4-2 first set lead only to see Williams run off five of the next six games to take the set.
Picking up an injury to her right ankle, the 16th seed faced 0-40 in the second game of the second set, Yastremska held in that game and blitzed through the rest of the set, losing just one more game to level the match.
The final set stayed on serve until Yastremska broke for a 5-4 lead, but she was unable to serve out the match. After a third straight break gave the Ukrainian a second chance to close it out, she did so to advance to the second round.
"I'm happy that I won and same time very sad because I had really good opportunity the first set", she said following the victory. "But when I twisted my ankle, to be honest, my mind went completely the other way. I started to think just about the pain, how it twisted, and what is going to be next.
"I really wanted to withdraw after the first game [of the second set] when I lost, but after that, the second game when I was serving, I [said] to myself that I'm not going to withdraw, that I'm going to play to the end. It doesn't matter how it's going to finish, but I have to finish that match. I have to deal with the pain."
Azarenka, Alexandrova upset highest seeded players in action
The first match of the day saw Ekaterina Alexandrova knock off ninth seed Elena Rybakina 7-5, 7-6 (6). The Russian got off the mark first, breaking midway through the opening set for a 4-2 lead, but a game that saw three double faults handed the break back to Rybakina.
The set stayed on serve until the 12th game, Alexandrova rifled a forehand to break and take the set. The Kazakh saved a break point in the second game of the second set and neither player was able to break. A tiebreaker ensued with Rybakina jumping out to a 5-2 lead.
Squandering two set points at 6-4, Rybakina double-faulted on the first and saw Alexandrova blister another winner on the second. Another ace brought up match point and a backhand winner sealed the upset.
"It feels great", she said. "It gives me a lot of confidence to beat players like her - but every match right now gives you confidence, because it was such a long pause. Every match is important now."
Azarenka had little difficulty in dispatching 12th seed Donna Vekic 6-2, 6-3 to pick up her first career win against the Croat. The two-time major champion hit 21 winners, including seven aces and broke Vekic's serve five times in the 71-minute match.
"I'm very happy to honestly win a match", she stated. "It's been a year or so. I haven't played a lot, but it's still like to get over that mid-hump a little bit and to be able to close out a match and stay strong throughout was super important to me."
Anisimova, Sakkari, Muchova among other winners
In an all-America matchup, Anisimova posted a routine 6-3, 6-3 victory over 11th seed Alison Riske. 13th seed Maria Sakkari dominated Cori Gauff 6-1, 6-3 while Karolina Muchova beat qualifier Ann Li 6-4, 6-4 to advance to face fourth seed Naomi Osaka.
Bernarda Pera will be Yastremka's next opponent after a 6-3, 1-6, 6-3 win over Heather Watson. Veronika Kudermetova came from behind to knock out Ajla Tomljanovic 5-7, 6-3, 7-5 to book a clash with top seed Karolina Pliskova. Kristina Mladenovic beat Anastasija Sevastova 6-3, 6-4.
Finally, Alize Cornet was victorious over wild card Caty McNally 6-0, 6-4 where Australian Open champion and second seed Sofia Kenin awaits.