BRISBANE, Australia - Unseeded Anett Kontaveit sprang a major upset at the Brisbane International, knocking out No.4 seed Petra Kvitova in straight sets to reach the quarterfinals.

The Estonian came into Brisbane looking to continue the positive momentum from 2018 that saw her reach career-high ranking of World No.20. She’s certainly made a great start to that goal in the new year, taking down Kvitova 7-5, 7-6(1) after an hour and 38 minutes.

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“I think these matches have definitely given me some confidence, and I feel like I can compete with the Top 10 players,” Kontaveit said of her 2018 breakthroughs. “I have that inner confidence feeling like when I go on court, anything is possible.

“There's not too much pressure [on me] with the rankings. When I play Petra, I mean she's Top 10. I think she has a bit more pressure than I do.”

The 2011 Brisbane champion Kvitova had to bounce back quickly following yesterday’s heroics against Danielle Collins: she was two points away from defeat before completing the comeback to win 6-7(6), 7-6(6), 6-3 after a three-hour thriller. By contrast, Kontaveit needed just 52 minutes to dismiss Carla Suárez Navarro 6-0, 6-3 in her own Auckland opener two days ago.

There was not much separating the two players in the early exchanges - there were no break points on offer for the first 10 games of the set, both players dialled in from the start and firing winners off both wings. Kontaveit would chip away at Kvitova’s defenses with acute-angled forehands, but the Czech covered the court well and returned everything with interest.

It was Kontaveit who finally drew first blood, keeping Kvitova under pressure and forcing the errors. She was rewarded with the first break of the match at a crucial time, leading 6-5, and served it out with confidence to edge through the opening set.

Kvitova found her range in the second set, however, as she charged ahead to a 2-0 lead, but the Estonian grabbed the break straight back, showing her grit to get them level to 2-2 .

The set continued to unfold in tortuous manner: Kvitova broke once more at 4-2 and then powered ahead to love hold that put her within touching distance of the second set, but Kontaveit again pulled them back level with a late break at 5-4.

With both players deadlocked, the pair matched into a tiebreak, where Kontaveit bossed proceedings and pushing Kvitova back behind the baseline with her powerful groundstrokes. Kontaveit dropped just one point during the tiebreak, completing the victory in emphatic style to claim her ninth career Top 10 win.

Up next, Kontaveit will take on the ever-dangerous Lesia Tsurenko of Ukraine, who ended local wildcard Kimberly Birrell’s Brisbane run in straight sets yesterday.

“I think the main thing for me right now is to keep improving and working on the things that I am working on,” Kontaveit said. “I think some things definitely have shown on court. Like my serve's been better than last year, and, yeah, I think I'm very happy with the improvements and the way they've shown this week.”