DOHA, Qatar - Ons Jabeur kicked her 2020 season into high gear at the Qatar Total Open, outlasting former World No.1 and 2017 champion Karolina Pliskova, 6-4, 3-6, 6-3 to book her spot in the quarterfinals.

Jabeur narrowly lost to reigning Wimbledon winner Simona Halep just last week at the Dubai Duty Free Tennis Championships, but held firm even as she appeared to struggle physically at the finish line, serving out the Centre Court upset - her biggest completed win by ranking - after one hour and 47 minutes.

"I had to play really good, she's a tough player and especially her serve it's not easy to break, so I had to really serve good or be ready for her returns," she said after the match.

"I know when I chose to receive at the beginning it was opportunity to try to break her at the beginning, it worked pretty good. She served amazing on break points, so I was kind of frustrated sometimes because when I play the point and I miss the ball easy I know it's not going to be that easy at the end to return her serves.

"But I'm glad that I maintained really good game and I'm looking forward for the next match."

The Tunisian was already in the midst of a breakthrough year after reaching her first Grand Slam quarterfinal at the Australian Open - where she fell to eventual champion Sofia Kenin - and is backing that result up with some style in Doha, making it into the third round without dropping a set. Still, she hadn't beaten a Top 10 player since 2018, when she shocked Sloane Stephens in straight sets en route to the Kremlin Cup final.

Seeded No.3 in Doha, Pliskova was aiming to recalibrate after suffering a third round defeat in Melbourne. She appeared in fine form on Tuesday when she breezed past Bernarda Pera. With her unique style and audacious shotmaking, Jabeur was going to always pose a threat to the 2016 US Open finalist, who won their last meeting in three sets last summer in Flushing Meadows.

She broke Pliskova in the first game of the match and made it through the opening set without facing a break point on her own serve, serving out the set to love.

It took just one break in the second set, as well, but this time it was the 27-year-old Czech who took the initiative, saving a break point to eventually take a 3-1 lead and hold on to level the match at one set apiece.

A marathon sixth game seemed to turn the tide for Jabeur in the decider as she scored the first break - to the delight of an enthusiastic Tunisian contingent in the stand. While Pliskova quickly broke back, Jabeur managed to will her way over the finish line, even as she grimaced with an apparent injury concern.

"I had a sharp pain on my hamstring, right hamstring, when I was going for the forehand at 4-2 my serve," she explained.

"I didn't really want to call the physio, so people would not think that I'm doing it on purpose, and plus I didn't want to break the rhythm I was trying to maintain. It was really difficult at the end to jump, but, I mean, she kind of helped me with making mistakes, which I'm glad that really happened on her serve. I managed through and I'm really happy that I did that."

Racing out to a 40-0 lead in the final game, the 25-year-old needed just two match points to put herself into the last eight, where No.8 seed Petra Kvitova awaits.

Kvitova, who won the title in Doha back in 2018, also took three sets to defeat former French Open champion Jelena Ostapenko earlier in the day.

"I mean Petra is Petra. She plays unbelievable and she's a tough player. We played at Wimbledon, so hopefully I can be ready more this time. It's different surface, it's a great tournament for me for now.

"She's a lefty, so she could really bother me with her serve. So I think I'm going to be ready, I'm much better than last year, so I have really high hopes for tomorrow.

"Hopefully, my hamstring will be better. I'm going to do my best tonight to recover and honestly I think it's going to be a great match."

In all, Jabeur struck an impressive 33 winners to just 18 unforced errors, and returned well enough to allow just four aces from Pliskova - the self-styled Ace Queen - who struck 20 winners to 22 unforced errors.

Jabeur outlasts Pliskova for career win in Doha