Williams continued her march through the early rounds of 2019's first Grand Slam tournament. She made quick work of 18-year-old Dayana Yastremska with a 6-2, 6-1 win that took 67 minutes.
Halep didn't have to exert much more energy in a dominant 6-2, 6-3 triumph over Venus Williams. The No. 1 seed needed 77 minutes to end the elder Williams sister's hopes of playing Serena for the first time at the Australian Open since the 2017 final.
On the men's side, there were no major upsets on the way to the fourth round. No. 1 Novak Djokovic dropped his first set of the tournament in a 6-3, 6-4, 4-6, 6-0 win over No. 25 Denis Shapovalov.
Selected Saturday Results
No. 1 Novak Djokovic def. No. 25 Denis Shapovalov: 6-3, 6-4, 4-6, 6-0
No. 4 Alexander Zverev def. Alex Bolt: 6-3, 6-3, 6-2
No. 11 Borna Coric def. Filip Krajinovic: 2-6, 6-3, 6-4, 6-3
No. 28 Lucas Pouille def. Alexei Popyrin: 7-6 (3), 6-3, 6-7 (10), 4-6, 6-3
No. 1 Simona Halep def. Venus Williams: 6-2, 6-3
No. 4 Naomi Osaka def. No. 28 Su-Wei Hsieh: 5-7, 6-4, 6-1
No. 6 Elina Svitolina def. Shuai Zhang: 4-6, 6-4, 7-5
No. 17 Madison Keys def. No. 12 Elise Mertens: 6-3, 6-2
No. 16 Serena Williams def. Dayana Yastremska: 6-2, 6-1
Full results can be found at the Australian Open's official website.
Williams has dominated the head-to-head rivalry with Halep. The 23-time major champion is 8-1 against the WTA's top-ranked player, with her lone loss coming in the round robin of the 2014 WTA Finals, which Serena went on to win by beating Halep in the final.
Despite that track record, Halep has confidence she can turn things around.
"For sure she's the best player in the world because she won so many grand slams," Halep told reporters after knocking off Venus. "She's been a lot on No 1. I cannot compare my results to her. But in this moment, I am confident that I am in this position, and I'm positive about it."
Another factor working in Serena's favor is time spent on the court this week. None of her three matches has lasted more than 70 minutes, and her opponents haven't won more than two games in a single set.
Halep, on the other hand, needed more than two hours to win each of her first two matches. She took advantage of sloppy play from Venus, who committed 33 unforced errors, and seemingly put the ball wherever she wanted:
While Serena and Halep commanded most of the attention, fourth-ranked Naomi Osaka had to overcome her first real adversity of the tournament to beat No. 28 Su-Wei Hsieh 5-7, 6-4, 6-1.
The first set was particularly troubling for Osaka because she had a 7-0 advantage in aces and Hsieh committed five double-faults. The defending U.S. Open champion lost it thanks to 20 unforced errors and having her serve broken three times.
Osaka was able to turn things around by committing just 22 unforced errors in the next two sets combined. She even found time to joke with the fans during an embarrassing moment in the second set:
Next up for Osaka will be 13th-ranked Anastasija Sevastova, who has followed her run to the U.S. Open semifinal last August by tying her deepest run at the Australian Open.
Djokovic's win over Shapovalov was more notable for the Serbian's outburst during the third set that resulted in him receiving an unsportsmanlike conduct violation from the chair umpire.
Per Simon Briggs of the Telegraph, Djokovic was frustrated with the lights in Rod Laver Arena and was heard shouting obscenities in his native language.
"I misconducted myself verbally," Djokovic said of the incident. "That why I got the code violation. I mean, it's not the first, nor the last time."
It's likely not a coincidence the outburst occurred during the set Djokovic wound up losing. He had no problems putting it behind him, with a clean sweep in the fourth set to seal the win.
As long as Djokovic controls his emotions on the court, nothing in his performance through the first three rounds suggests he won't be among the last men vying for the Australian Open title when the final weekend comes around.