A week ago, Karolina Pliskova had a terrific run at the Transylvania Open, winning five matches and her first title in four years. And then, after a 10-hour flight from Cluj-Napoca, Romania to Doha, Qatar, she grabbed four hours of sleep and began the process all over again.

After winning a trio of three-set matches, Pliskova will meet resurgent Naomi Osaka in a Thursday quarterfinal at the Qatar TotalEnergies Open. It will be Pliskova's ninth match in 10 days.

The Czech Republic's Pliskova, who turns 32 next month, is only one of a handful of surprises in the final eight of this Hologic WTA Tour 1000 event. No.1 Iga Swiatek and No.3 Elena Rybakina are the only seeded players remaining in the draw.

While Victoria Azarenka isn’t seeded, this is her 36th WTA 1000 quarterfinal, tied for No.3 all-time with Petra Kvitova and Caroline Wozniacki. Azarenka's straight-sets win over Jelena Ostapenko was her 22nd in Doha, equaling Kvitova’s leading total since the tournament’s inception in 2001.

Azarenka will now face Swiatek in a quarterfinal match between two-time Doha champions. Swiatek leads the head-to-head 2-1.

A brief accounting of the other unseeded competitors and their Thursday matchups:

Leylah Fernandez -- The Canadian teenager blazed into our consciousness by sweeping into the finals of the 2021 US Open. Since then, Fernandez’s record in Grand Slams is 9-8.

So, after stunning Zheng Qinwen 7-5, 6-3, how does the No.38-ranked player find herself on the threshold of her first WTA 1000 semifinal? The power of positivity.

Fernandez trailed Zheng 5-3 in the first set and came back to win four straight games with some great defense and sharp angles.

“We’ve been working a lot on staying positive in tough moments, trying to change the mentality from negative to positive,” Fernandez said afterward. “Especially 5-3 down, I looked at my box and they looked at me and pointed to their head and I knew exactly what that meant.

“And I guess that just changed the whole process in how the match went. Zheng Qinwen, she’s off to an amazing start for the year. Finals of a Grand Slam, Top 10 -- so it’s not very easy to play against a player like that.”

Now 21, Fernandez's next assignment won’t be easy, either. It’s her first up-close, across-the-net look at No.3 seed Rybakina.

Naomi Osaka -- For the record, she’s ranked No.747, but that’s only because she left the Tour for an extended maternity break.

Understandably, the four-time Grand Slam champion looked a bit sluggish in her return, losing three of her first four matches. In Doha, however, she has been in encouraging form.

In the opening round, she avenged her first-round Australian Open loss to Caroline Garcia. That was followed by a three-set win over Petra Martic and a walkover in the third round when Lesia Tsurenko pulled out with an elbow injury.

“Honestly after Abu Dhabi [and a first-round loss to Danielle Collins], I actually have more confidence in myself now, which is a little strange,” Osaka told reporters. “I think that, for me, was the worst thing that could happen. I feel like since I have seen the worst that can happen, I think everything else is a plus.

“In Australia I know that I said I was only going to play Dubai, so I feel like I have to take these tournaments as extra credit.”

And now, in a nice piece of symmetry -- and extra-extra credit -- Osaka can avenge a second-round Brisbane loss to Pliskova when they meet in the quarterfinals.

Karolina Pliskova -- The Czech Republic, despite its relatively diminutive size, keeps pumping out the talent. Pliskova, a former World No.1, took on rising Czech teenager Linda Noskova in the third round -- and the veteran won, 3-6, 7-5, 6-1.

Tired though she may be, Pliskova has now won eight consecutive matches. This, after taking off the tail end of the 2023 season to heal both mentally and physically. She’s in the mix for her third career WTA 1000 title, after 2016 Cincinnati and 2019 Rome.

Pliskova leads the head-to-head with Osaka 4-2, but before this year’s Brisbane encounter they hadn’t met in four years.

Pliskova pulls off comeback vs. Noskova, wins eighth straight match

Danielle Collins -- The 2022 Australian Open finalist scuffled at the outset of 2024, losing three of five matches. She was forced to qualify in Abu Dhabi, then beat Osaka and pushed Rybakina to three sets.

After winning two more qualifying matches in Doha, she upset No.13 seed Veronika Kudermetova, then beat Marie Bouzkova and Katerina Siniakova -- who had upset No.2 seed Coco Gauff.

“Just proud of my effort to come out here and play so many matches back to back and maintain a high level,” said the No.63-ranked Collins. “Maintaining a high level of physicality but also tactically sticking to what’s working.”

Next up: Anastasia Pavlyuchenkova, who she’s beaten all three times they’ve played. If it happens again, Collins will be into just her second WTA 1000 semifinal -- in the season she’s said will be her last.

Anastasia Pavlyuchenkova -- Nearly 15 years ago, Pavlyuchenkova made the semifinals at Indian Wells, losing there to Ana Ivanovic.

Now, at age 32, Pavlyuchenkova is on the verge of what would be her fourth WTA 1000 semifinal; she also made the final four at 2010 Cincinnati and 2021 Madrid. Of these five surprise quarterfinalists, she’s ranked the highest, at No.32.

She’s done a lot of heavy lifting here, moving past No.11 seed Daria Kasatkina in the first round, Marta Kostyuk in the second round and No.6 seed Marketa Vondrousova 7-5, 6-3 in the third round.