Alas, all the winner will earn Monday is a quarterfinal berth. And while Halep is the one who leads the tournament seedings and the WTA rankings right now, and is the one who more recently collected a major title, she is well aware of Williams' standing in the sport.
The American's No. 16 seeding means nothing in terms of the level of her tennis. It merely reflects how infrequently Williams has played over the past two years while she was pregnant and then gave birth.
"In my opinion, to be No. 1 in the world and to be the best player in the world — it's a little bit different. In this moment, I'm No. 1 in the world, so I will take that. I feel like I have been there many months, many weeks," Halep said. "But for sure, she's the best player in the world, because she won so many Grand Slams. ... I cannot compare my results to her."
That's certainly an honest take. It's also certainly the case. Halep's lone Grand Slam trophy came at last year's French Open — she's been the runner-up three other times, including a year ago at the Australian Open. Williams, meanwhile, is trying to earn an eighth championship at Melbourne Park and a 24th major overall, which would equal Margaret Court's all-time record.
Asked whether the pursuit of Court is in the back of her mind as she edges closer to the mark, Williams joked: "I've been 'edging closer' for probably like a decade now. I'm not even dealing with that right now."
Theirs is by far the most intriguing women's fourth-rounder on Monday's schedule. The others: No. 4 seed Naomi Osaka vs. No. 13 Anastasija Sevastova; No. 6 Elina Svitolina vs. No. 17 Madison Keys; No. 7 Karolina Pliskova vs. No. 18 Garbine Muguruza.
"For sure, the best match now in the draw, in the tournament," said Pliskova, who upset Williams in the 2016 U.S. Open semifinals and predicted: "She's going to put a lot of pressure on Simona." Halep struggled through a pair of three-setters in her opening two matches but was in much better form Saturday during a 6-2, 6-3 victory over Williams' sister, Venus.
This will be the 25th time that a woman faced the two Williams siblings in consecutive matches at the same event; on seven of those occasions, the player beat both. Only once has someone done that — defeated the sisters in back-to-back matches — and gone on to win a Grand Slam title: Justine Henin at the 2007 U.S. Open.
"Definitely is the toughest draw I've ever had," Halep said. "A huge challenge." Serena, meanwhile, was not challenged at all during Week 1, dropping a total of nine games through three matches. As dominant as she's looked thus far, she offered a typical-for-her assessment when asked whether she senses that she is back at the height of her powers.
"I think I'm getting there," came the reply. "I don't feel like I'm there yet." She'll carry an 8-1 career head-to-head advantage over Halep into Monday; their last match came back in 2016. Halep acknowledged she used to cower at the thought of facing Serena. The Romanian also insisted those days are gone.
"Now I don't feel intimidated anymore," Halep said. "I have huge respect for her because she's a great champion, but she's just an opponent."
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