The fourth round of the 2023 Australian Open is set. Here are the key facts and numbers behind the last 16 players standing:

Day 6 from the Australian Open

5 - Remaining Grand Slam champions from the 12 who started in the main draw. Victoria Azarenka is the only previous Australian Open winner (2012, 2013). The others are Iga Swiatek (Roland Garros 2020, Roland Garros 2022, US Open 2022), Elena Rybakina (Wimbledon 2022), Barbora Krejcikova (Roland Garros 2021) and Jelena Ostapenko (Roland Garros 2017).

3 - Players remaining who have won a WTA singles title in 2023. Both Adelaide 500 champions, Aryna Sabalenka and Belinda Bencic and Auckland champion Coco Gauff. Additionally, Jessica Pegula, who spearheaded the U.S. victory at the inaugural United Cup, is also still in the draw.

Gauff is on an eight-match winning streak, while Sabalenka, Bencic and Pegula are on seven-match winning streaks. One of those is guaranteed to end in the fourth round as Sabalenka and Bencic clash.

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2 - Polish women in the second week after Magda Linette joined Swiatek with a 6-3, 6-4 defeat of No.19 seed Ekaterina Alexandrova in the last third-round match to be completed. The only previous Grand Slam last-16 lineup in the Open Era that featured two Polish women was the 2008 Australian Open, when Agnieszka Radwanska reached the quarterfinals and Marta Domachowska the fourth round. 

1 - Guaranteed new Australian Open semifinalist following Elise Mertens' loss to Sabalenka. The bottom quarter will also feature two new Australian Open quarterfinalists. Sabalenka, Bencic and Donna Vekic have all reached the fourth round here before, but never gone beyond it. Linda Fruhvirtova is making her tournament debut.

The bottom half has also been guaranteed a first-time finalist since Garbiñe Muguruza's first-round exit. The only player remaining in it who has made the last four here before is 2019 semifinalist Karolina Pliskova.

2 - Teenagers remaining in the draw from the seven who started in it: Fruhvirtova, 17, and Gauff, 18. Fruhvirtova is the fifth player since 2010 to reach the second week of a Slam before turning 18, joining Belinda Bencic (US Open 2014), Amanda Anisimova (Australian Open and Roland Garros 2019), Swiatek (Roland Garros 2019, during which she had her 18th birthday) and Gauff (Wimbledon 2019 and 2021, Australian Open 2020, Roland Garros 2021).

Fruhvirtova is the first 2005-born player to reach this stage of a major, and takes over from Gauff as the youngest active player to do so.

4 - Unseeded players left: No.45-ranked Magda Linette, No.64-ranked Vekic, No.82-ranked Fruhvirtova and No.87-ranked Zhu Lin. Vekic is a former No.19 making her way back from injury; Fruhvirtova and Zhu have both hit their career-high rankings (No.74 and No.58 respectively) within the past four months.

3 - Players in the second week of a major for the first time: Linette, Fruhvirtova and Zhu. Additionally, Rybakina and Ostapenko are making their debuts in the second week at the Australian Open. Linette had been 0-6 in Grand Slam third round matches -- a joint record for third round appearances without a fourth round among active players, now held solely by Lauren Davis.

7 - Players remaining who have yet to drop a set: Swiatek, Gauff, Pegula, Krejcikova, Pliskova, Sabalenka and Bencic. Pegula has spent the least amount of time on court so far at 3 hours and 35 minutes, closely followed by Pliskova at 3 hours and 38 minutes. Caroline Garcia has spent the most amount of time on court so far at 5 hours and 7 minutes, followed by Zhu at 5 hours and 5 minutes.

6 - Players in the last 16 who have a positive win-loss record in this round of a major: Rybakina (2-1), Ostapenko (3-1), Pegula (4-0), Krejcikova (3-2), Azarenka (17-10) and Pliskova (10-3).

Two players have a negative record in Grand Slam fourth rounds: Garcia (2-5) and Vekic (1-3). The remainder have a level record: Swiatek (5-5), Gauff (3-3), Zhang Shuai (2-2), Sabalenka (3-3), Bencic (3-3) and the three first-timers at 0-0.