Zheng Qinwen reached her first quarterfinal of the 2023 season with a 7-6(10), 6-1 upset of No.5 seed Jelena Ostapenko at the Mubadala Abu Dhabi Open after saving three set points in the first set.

It was Zheng's second win over Ostapenko in as many meetings, having already defeated the Latvian 6-3, 3-6, 6-4 in the first round of last year's US Open. Reprising that result puts the 20-year-old into her third quarterfinal at WTA 500 level or above in the past seven months, following Toronto last August and a maiden tour final in Tokyo last September.

Zheng will next face either No.1 seed Daria Kasatkina or Jil Teichmann as she bids to reach the last four in Abu Dhabi.

No.4 seed Veronika Kudermetova was also victorious, overcoming former doubles partner Elise Mertens 6-1, 7-5. Kudermetova led 5-2 in the second set, but had to hold off an attempted comeback by Mertens, who saved two match points and levelled at 5-5.

Highlights: Kudermetova d. Mertens

Kudermetova had lost her first four meetings with Mertens at pro level, as well as both of their junior encounters, but has now captured two wins in a row against the Belgian. She will face either No.8 seed Liudmila Samsonova or former Roland Garros champion Barbora Krejcikova in the quarterfinals.

First-set moments: The 1-hour, 58-minute contest comprised two vastly contrasting sets. The first was a nip-and-tuck affair that saw momentum swing back and forth, culminating in the second-longest tiebreak of the season so far (by score). Only Nuria Parrizas Diaz's 7-6(11), 6-2 defeat of Beatriz Haddad Maia at the Australian Open exceeded it.

Ostapenko had the brighter start, firing winners and slamming down unreturnable serves to leap out to 4-1. But a loose, error-strewn service game allowed Zheng back in, and the Chinese player responded with a four-game run of her own to lead 5-4. Fierce returning from Ostapenko prevented Zheng from serving out the set, though.

Former Roland Garros champion Ostapenko held the first three set points of the opener, the first at 6-5 on Zheng's serve and the next two in the tiebreak, but could not convert any of them; Zheng's brilliant return winner to save the second was one of the most crucial points of the match.

The World No.29 needed four set points of her own to seal the set, but converted as Ostapenko went long off an awkward short ball. The tiebreak was the longest of Zheng's pro career, and the second overtime tiebreak she has won this year following her  6-1, 4-6, 7-6(7) defeat of Anett Kontaveit at Adelaide 1.

By the numbers: Zheng tallied 21 aces during her US Open win over Ostapenko, the most in a single match of the 2022 WTA season. Once again, she hit double figures on that front, with aces accounting for 10 of her 28 winners today. Conversely, Ostapenko suffered from a rash of eight double faults; three came serving at 4-4 in the first set and another two in the tiebreak, including on its penultimate point.

In total, Zheng fired 28 winners to Ostapenko's 20, and committed 22 unforced errors to her opponent's 25.

The tiebreak in Zheng's words: "I just play in the moment and focus on my game. Even if I'd lost the first set, there were still two more sets to go -- so whatever happened, I'd fight to the end."