There are only two players left in this Australian Open draw who have yet to lose this year. Aryna Sabalenka and Coco Gauff have shimmering athletic talent, but they’ll both tell you it’s what’s between the ears that makes a champion.

During her fraught second-round match with Clara Tauson, Sabalenka thought to herself, “Oh, my God, I’m really tough.”

Later she told reporters, “Over the years, I struggle a lot with different stuff. I think all of those difficult experiences make me a really, really tough, tough person.”

Gauff, meanwhile, has learned to immerse herself in the process -- to not dwell on the potential result. That’s the difference in the two Grand Slam finals she’s played -- the 2022 French Open and the 2023 US Open.

“The first final, I felt close, and I think that’s why I got tight and couldn’t really overcome the nerves,” the 20-year-old Gauff explained. “The second final, it felt so far away, so I was able to play free because I felt like I had so much more work to do.”

The No.1-seeded Sabalenka and No.3 Gauff are both 8-0 this season and have yet to lose a set in Melbourne. Sabalenka’s dropped 23 games and Gauff 20. They could well be headed to a semifinal showdown.

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But that’s a few rounds ahead. First there is the matter of these four tantalizing fourth-round matches from the top half of the draw:

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No.1 Aryna Sabalenka vs. No.14 Mirra Andreeva

Head-to-head: 3-1, Sabalenka, most recently two weeks ago in the Brisbane semifinal, with Sabalenka winning 6-3, 6-2. 

Andreeva had just turned 16 when she faced Sabalenka in the 2023 Madrid quarterfinals.

“I would say that I was so scared, to be honest,” Andreeva said. “I was so scared to hit the ball, and I was afraid of that big court and big stadium. So I was a bit tight and I was, like, `Oh, my God, what is going on?’ ”

Predictably, she lost that first meeting, winning four games. A year later, she got five against Sabalenka in Madrid’s Round of 16. The breakthrough came three weeks later at Roland Garros, when Andreeva won a marvelous three-set quarterfinal match.

But that match was on clay, which plays to Andreeva’s strengths. This one’s on the blistering fast courts of Australia, where Sabalenka rarely loses. In Brisbane, on the fourth day of the new year, Andreeva managed only five games.

“Now I know what to do, and I figured it out,” Andreeva said. “So I think that this time is going to be a bit better.

Andreeva was a 6-2, 1-6, 6-2 winner over No.23 Magdalena Frech in the second round. Sabalenka defeated Tauson 7-6 (5), 6-4.

Sabalenka has won 17 straight Grand Slam matches on hard courts, the first to do it since Naomi Osaka five years ago. She is attempting to win her third consecutive Australian Open title, something that hasn’t happened in more than a quarter century.

No.3 Coco Gauff vs. Belinda Bencic

Head-to-head: 1-1, with Bencic winning four years ago in the Adelaide 500 semifinals and Gauff taking their 2023 Washington, D.C. quarterfinal.

Bencic advanced after Naomi Osaka, down a set, retired with an abdominal strain she’s been nursing since Auckland. Bencic, who says she has yet to play her best tennis after giving birth last year, knows this one is going to be difficult.

“Coco, obviously one of the best players in the world right now,” Bencic told reporters. “I was able to watch her a little bit when I was just lying on the couch for the last nine months.

“At this moment, I still call this a little bit a test. I came here to see how it’s going to be. Obviously I didn’t expect to be in the fourth round.”

Gauff, a 6-4, 6-2 winner over No.30 Leylah Fernandez, did. She’s only the fifth female player in the Open Era to win her first eight matches for three consecutive years -- after Margaret Court, Steffi Graff, Monica Seles and Serena Williams.

Olga Danilovic vs. No.11 Paula Badosa

Head-to-head: 0-0.

Danilovic’s presence in the fourth round is the biggest surprise in the top half of the draw. The No.55-ranked left-hander upset No.7 seed Jessica Pegula 7-6 (3), 6-1.

“I mean, what can I say?” Danilovic said afterward. “I knew who I play, and I knew that I have to have my A, A, A, plus, plus, plus game for me to be even there and to compete with her.”

Later, the 23-year-old saw a video of fellow Serb Novak Djokovic cheering her on.

Pegula is the highest-ranked player Danilovic has ever beaten and her third Top 10 victory. Danilovic is attempting to become the first Serbian woman to reach a Grand Slam quarterfinal since Ana Ivanovic at Roland Garros in 2015.

Paula Badosa was a 6-4, 4-6, 6-3 winner over No.17 Marta Kostyuk. The 27-year-old Spaniard came in a lackluster 1-2 but seems to have found some confidence.

“Yeah, we’ll forget the tournaments before -- we start in Australian Open,” Badosa said. “I work a lot with my psychologist to stay in the moment. It’s tough because sometimes the mind goes everywhere, but when I achieve that to stay in that moment, to play point after point, I think it’s when my level increases

“Really looking forward to the second week, and I know now the level will be even higher, better players. So I’m ready for the challenge.”

No.18 Donna Vekic vs. No.27 Anastasia Pavlyuchenkova

Head-to-head: 2-0, Pavlyuchenkova, including last year’s win in the first round of the Australian Open.

After two difficult three-set matches, Pavlyuchenkova was a 6-1, 6-2 winner over Laura Siegemund -- the easiest top-half victory in the third round. The 33-year-old is one of three active players with 90 or more Grand Slam match-wins not to win a major title. This is her 11th Round of 16 in a major but her first after going 0-for-5.

Vekic beat No.12 Diana Shnaider in a barnburner, 7-6 (4), 6-7 (3), 7-5, that required nearly three hours. Last year’s Olympic silver medalist in singles has now won 16 matches at the Australian Open, her most in the Slam. It’s the first time she’s put together three straight wins in four months.