After a day off because of COVID-19 concerns, the players are set to return to Melbourne Park for the trio of WTA 500 events at the Gippsland Trophy, Yarra Valley Classic and Grampians Trophy.

Because of the postponement, the scoring format will change to a best-of-two regular tiebreak sets with a 10-point match tiebreak if required for a final set. 

Friday’s matches feature no fewer than eight former Grand Slam champions, and one of those is a rematch of last year’s Australian Open final. The five top-ranked players in the world -- Ashleigh Barty, Simona Halep, Naomi Osaka, Sofia Kenin and Elina Svitolina -- will give it a go.

So will Serena Williams and her stellar resume of 23 major titles.

Here's how you can follow all the action, along with some notable matches to watch: 

Gippsland Trophy

No. 1 Simona Halep vs. No. 9 Ekaterina Alexandrova

The world No. 2 handled Laura Siegemund 6-2, 6-4 and, in a mild upset, Alexandrova got past reigning French Open champion Iga Swiatek 6-4, 6-2.

2021 Gippsland Trophy Highlights: Halep beats Siegemund to seal QF spot

Thus, Halep avoids a rematch with Swiatek, who took her out in the fourth round at Roland Garros last fall. Still, this won’t be easy. These two have met twice before, with the No. 33-ranked Russian winning three of five sets.

“At the beginning of the year it’s always tough, so we cannot say one player has to win, is favorite, because they don't have matches and it’s tough to find the rhythm,” Halep told reporters afterward. “[Alexandrova’s] playing flat, as I remember well, flat and very deep. So it’s going to be tough to return the balls, but I have to play my game.”

No. 8 Karolina Muchova  vs. Kaia Kanepi

It’s happening again; Kanepi, the oldest player in this draw, at 35, is doing damage.

After ending Aryna Sabalenka’s 15-match winning streak in the second round, the  Estonian moved past Daria Kasatkina 7-5, 6-1 to set up her first-ever meeting with Muchova. Kanepi, at No. 94, is the lowest-ranked quarterfinalist.

Ranked No. 27, Muchova needed three sets to get past Jasmine Paolini of Italy. She was one of four Czechs to reach the round of 16. The two have never played.

No. 3 Elena Svitolina vs. No. 7 Elise Mertens

Svitolina dropped a first-set tiebreaker, but rallied to defeat 2017 French Open champion Jelena Ostapenko. The 26-year-old from Ukraine has now reached her sixth quarterfinal of the previous seven tournaments.

Meanwhile, Mertens managed No. 12 Caroline Garcia 7-6 (1), 6-3. In her most recent outing last November, the 25-year-old Belgian advanced to the final in Linz before losing to Sabalenka.

Svitolina has won three of four head-to-head matches, but Mertens’ lone victory came on these grounds at the 2018 Australian Open.

“It feels like almost normal again because people can come and watch,” Mertens said later. “It makes a difference. There's nothing to complain about. Of course, I just want to play some matches. Of course, I want to win some matches, too.”

No. 2 Naomi Osaka vs. Irina-Camelia Begu

She’s a longshot in these quarterfinals, and she played the longest match to get here.

Begu, the 30-year-old Romanian, staged a memorable victory over No. 5 seed Johanna Konta, 4-6, 7-6 (10), 7-6 (4). The match required a total of 253 points and a staggering literally 3 hours, 35 minutes.

Osaka dropped the first set, but rallied to overtake Katie Boulter, 3-6, 6-3, 6-1. She now owns an unbeaten streak of 13 matches; her last loss was one year ago, playing a Fed Cup match for Japan, to Sara Sorribes Tormo.

“I felt the entire first set and sort of halfway into the second set, I felt like I was on my back foot a lot,” Osaka said in her post-match press conference. “I felt like I was letting her dictate most of the balls. I think in the second and third set I was sort of able to find what I needed to do, sort of impose my pace onto the rally.”

This is a first-time encounter.

Yarra Valley Classic

No. 1 Ashleigh Barty vs. Shelby Rogers

After an 11-month layoff, the Australian finds herself in the quarterfinals on very familiar ground. She needed three sets to ease past No. 16 Marie Bouzkova after a straight-sets second-round win.

Rogers, the unseeded 28-year-old American, upset No. 7 Petra Martic 7-6 (1), 6-3. It’s been a difficult few years for Rogers, but she reached the quarterfinals at last year’s US Open (beating Petra Kvitova in the fourth round) before falling to eventual champion Naomi Osaka.

The precedent is the 2017 Australian Open, when Barty won a second-round match is straight sets.

“Yeah, it’s always nice to test the legs and get into those tougher matches obviously,” Barty said afterward. “You know what you're going to get and you know that you’re going to have to produce your best tennis over a long period of time, so I think that was the challenge today to make sure that I didn’t just bundle up like a bag of spuds and lose what was happening.”

No. 5 Serena Williams vs. No. 13 Danielle Collins

In the biggest upset so far, Collins took down No. 3 Karolina Pliskova in a taut one, 7-6 (5), 7-6 (3).

That sets up an All-American encounter with Williams, the seven-time Australian Open champion who breezed past Svetana Pironkova 6-1, 6-4.

Getty Images

To review: Since coming recovering from last year’s Achilles injury, Serena has beaten Naomi Osaka in an Adelaide exhibition and won all four sets in Melbourne. Her serve has yet to be broken.

“It’s finally getting better,” Serena said of her Achilles, “which I’ll do anything not to have that injury, because it actually affects my life. Like, I feel like knee injuries are different, but this Achilles injury is you physically can’t walk.

“What we have been doing lately with my team and my physio, we have just been -- every day they have been just killing me with different exercises to do for it.”

Oddly enough, Williams and Collins have never faced off.

No. 8 Marketa Vondrousova  vs. No. 14 Nadia Podoroska

Certainly, these players will be a little fatigued when they meet for the first time.

It was Podoroska emerging from Wednesday’s last match, upsetting No. 4 Petra Kvitova 5-7, 6-1, 7-6 (7) in a match that ran 2 hours, 40 minutes. Kvitova was up 5-2 in the tiebreaker but committed four consecutive errors.

Vondrousova crept past Vera Zvonareva  7-6 (4), 6-7 (4), 6-4 that consumed nearly three hours.

Podoroska, a 23-year-old from Argentina, reached the semifinals at Roland Garros last year, losing to eventual champion Iga Swiatek.

No. 2 Sofia Kenin vs. No. 6 Garbine Muguruza

Here is your marquee match for Friday: It’s a rematch of last year’s Australian Open final, won by Kenin in three sets.

On Wednesday, Kenin ran her winning streak at Melbourne Park to nine matches with a 5-7, 7-5, 6-2 victory over fellow American Jessica Pegula in a match that ran over two hours. Muguruza had a much easier time with No. 11 Anastasia Pavlyuchenkova, winning 6-1, 6-2 in a scant 57 minutes.

“It’s a good match to play,” Muguruza said of Kenin. “We played exactly almost one year ago, right, so it was a tough match. It was a special match, also, being a final. Looking forward to facing her again and try to turn the score around.”

Muguruza said she later went back and studied the match on video.

“I think that I have now more things to -- I know her a little bit better because we played already twice, so that's normal,” she added. “But yeah, I’m just looking forward in general just to play again these top players.”

Grampians Trophy

No. 1 Maria Sakkari vs. Leylah Fernandez

Fernandez was a 6-3, 6-1 winner over former Grand Slam champion Sloane Stephens.

2021 Grampians Trophy: Fernandez ousts Stephens in opener

Sakkari, who moved into the top-seeded spot when Bianca Andreescu pulled out, opened 2021 with four straight wins in Abu Dhabi, including victories over Kenin, Muguruza and Cori Gauff before losing to Sabalenka in semifinals.

Head-to-head: 0-0.

No. 2 Belinda Bencic vs. Sorana Cirstea

Cirstea arrives with a forceful 6-1, 6-1 victory over Oksana Kalashnikova.

Bencic reached a career-high ranking (No. 4) last fall, but only played once again in 2020. She missed last two Grand Slams because of COVID-19 concerns and a right arm injury.

Head-to-head: 0-0.

No. 3 Victoria Azarenka vs. Yulia Putinseva

Putinseva beat Georgina Garcia Perez 7-6 (1), 6-4.

Azarenka is a two-time Australian Open champion.

Head-to-head: 0-0.

No. 4 Elena Rybakina vs. Barbora Krejcikova

Krejcikova was a 6-4, 4-6, 6-4 winner over Lauren Davis.

Kazakhstan’s Rybakina, only, 21, is already 3-1 this year with a run to the quarterfinals at Abu Dhabi.

Head-to-head: 0-0