After upsetting World No.2 Naomi Osaka 6-4, 3-6, 6-1, Karolina Muchova was asked Sunday by an earnest reporter if she was surprised.

“Hmmm,” Muchova said, considering the question. “I wouldn’t say surprising.”

On the surface, it may have sounded arrogant, but it was an answer based in fact. After losing six of the first seven games in the Australian Open quarterfinals, the 24-year-old Czech Republic player came back to win 1-6, 6-3, 6-2. Her opponent? World No.1 Ashleigh Barty.

How has she managed to maintain that kind of mindset against the very best of the already elite?

“Well, I’m working on it,” Muchova said. “I think I’m getting better each match. It’s not specific preparation if I play Top 10 player or Top 20 or Top 50 player. It’s usually very similar, but yeah, I'm just trying to prepare as much as I can and as best I can.”

That best has been good enough to land Muchova in Tuesday’s Mutua Madrid Open Round of 16 encounter with No.16 seed Maria Sakkari (8 p.m. local, 2 ET)

It’s one of four sensational matches: World No.3 Simona Halep versus Elise Mertens (1 p.m. local), World No.7 Aryna Sabalenka versus Jessica Pegula (3 p.m.) and Australia Open finalist Jennifer Brady versus Anastasia Pavlyuchenkova (5 p.m.).

It’s been an oddly disjointed year for World No.20 Muchova, who withdrew from her first two events of the season, in Abu Dhabi and Melbourne. After racing into the semifinals at the Australian Open, she sat out for two months, nursing an abdominal injury. Her first tournament back, two weeks ago in Stuttgart, ended in a first-round loss to Ekaterina Alexandrova.

And now here she is, holding down the draw’s bottom line after defeating Osaka.

“I’m getting there,” Muchova said. “I’m still not 100 percent, I would say. It was a little bit tough after struggling with some muscle problems. I’m getting used to play again matches match by match and regenerate better and recover better. So, yeah, I feel like I’m close.”

The only time Sakkari and Muchova have played was a 2016 ITF $100,000 event in Sharm El Sheikh, Egypt. Sakkari won 6-4, 6-1 in a quarterfinal.

The total package

Osaka on Muchova: “I would say it’s tough playing her on clay because she hits quite a heavy forehand ball, and she uses that to dictate me around. I would also say her serve is really good. But there is not really a big flaw in her game. I also think she’s a great mover. So, yeah, she’s like a really good package player.”

Made for clay

There’s a reason Halep came out on top in the WTA Insider’s Clay Court Power Rankings. Kiki Bertens was a distant second in the complex calculus that crunches numbers over five years.

Halep said she was struggling before the clay season.

“I was stressed before the matches, but now I feel better,” she said. “I’m getting better mentally. I can say I started to enjoy more, and I don’t feel those negative nerves anymore. So I’m in a good place now.”

That’s bad news for the rest of the field.

Halep has nine clay titles, including her 2018 run at Roland Garros. She’s 4-1 against Mertens, the last two straight-sets wins coming in 2020 at the Australian Open and the final at Prague.

“I know that it’s difficult because she’s all the time going inside the court and she stays at the baseline and likes to hit all the balls,” Halep said of Mertens. “It’s going to be tough.”

Sabalenka seeking a first

Oddly enough, the only three times Sabalenka and Pegula crossed paths came in a span of four events last year.

Pegula won in three sets at the Western & Southern Open played on the grounds of the US Open. Days later, Sabalenka and Mertens teamed to beat Pegula and Shelby Rogers in doubles. Finally, Sabalenka won 6-3, 6-1 at the French Open last fall.

Watch 'em all: Sabalenka's 40 winners vs. Kasatkina in Madrid

That was the only match on clay. Sabalenka, the 22-year-old from Belarus, had a wonderful week in Stuttgart, beating Halep in the semifinals and pushing Barty to three sets in the final.

“This year I feel a little bit better on the clay, a little bit different,” Sabalenka said. “Yeah, actually it feels really good playing here. The clay is really like a little bit faster than it was before.”

Sabalenka is looking for the first clay-court title of her career; her nine victories have all come on hardcourts.

The good news? She can’t see Barty – who knocked her out in both Miami and Stuttgart – until the final.

Luck of the draw?

At No.41, Pavlyuchenkova is the lowest-ranked competitor left in the bottom half of the draw.

The 29-year-old Russian came into Madrid with a 5-8 record, but some of that was just bad luck. Among those she’s lost to: Naomi Osaka, the eventual champion, at the Australian Open, Garbine Muguruza, Petra Kvitova and Veronika Kudermetova.

Pavlyuchenkova took down two big hitters in Madrid, Madison Keys and No.6 seed Karolina Pliskova. Now, it’s No.11 seed Jennifer Brady, whom she’s never played.

Pegula jumps 30 spots

The last time she was here, two years ago, Pegula lost in qualifying. Now, she’s a win away from the quarterfinals of a WTA 1000. That’s the kind of season it’s been for the 26-year-old American.

She was ranked No.63 to start the year, then blasted through to a best-ever quarterfinal berth at the Australian Open. After winning three qualifying matches in Doha, she got to the semifinals before losing to Petra Kvitova. It was the quarters in Dubai and the round of 16 in Miami. She has beaten top 10 player Karolina Pliskova three times this year.

Pegula is ranked No.33, one spot below her career best, achieved last month.