No.4 seed Maria Sakkari opened her J&T Banka Ostrava Open campaign with a serving masterclass to defeat Jelena Ostapenko 6-4, 6-2 and reach her seventh quarterfinal of the year in 1 hour and 23 minutes.

Sakkari, a semifinalist here last year, conceded only seven points behind her delivery - three in the first set and four in the second. The pair had split two previous meetings in three sets, with Ostapenko winning 6-2, 4-6, 6-2 on green clay at Charleston 2017 and Sakkari gaining a 6-1, 3-6, 6-2 revenge on the Australian Open hard courts in 2019, but their first indoor encounter would also be the first decided in two sets.

It was a fiery encounter at times in terms of both tennis and temper, though both players concluded the match with a warm, sportsmanlike handshake at the net. Sakkari, whose year has been highlighted by a pair of Grand Slam semifinal runs at Roland Garros and the US Open, continues to show her career-best form on a consistent basis, while Ostapenko, runner-up in Luxembourg last week, can take the positives from the quality she has shown indoors this month.

Match management: Sakkari's supreme serving effectively shut Ostapenko out from ever getting a foothold on return. By contrast, the Latvian's own service games were constantly under pressure, with Sakkari nailing a succession of clean winners off the second serve return. The first three went to deuce - and though Ostapenko got out of each with some electric, clutch shotmaking, ultimately this tightrope walk was unsustainable.

Serving at 3-4, a flurry of errors gave Sakkari another break point - and this time the Greek converted, tracking an Ostapenko dropshot before essaying an exquisite high backhand volley winner. From that point on, Ostapenko's striking would become wild as she sought even bigger, better winners to hold Sakkari at bay. The high-risk strategy didn't pay off. Sakkari broke at the start of the second set with a forehand winner, sealed the double break as Ostapenko resorted to some ill-advised slice experiments, and coasted to victory thereafter.

Stat corner: Sakkari finished with an impressive ratio of 19 winners to 10 unforced errors, with only three of the latter coming in the second set. Ostapenko was able to deliver a fine balance in the first set with 11 winners to 13 unforced errors, but her collapse in the second was reflected in her 14 unforced errors to only four winners.

What's next for Sakkari: A quarterfinal clash with either No.5 seed Anastasia Pavlyuchenkova or local wildcard Tereza Martincova.

Rybakina survives Linette in three sets

Earlier, No.7 seed Elena Rybakina booked her place in her sixth quarterfinal of the season 6-3, 2-6, 6-1 over qualifier Magda Linette in one hour and 37 minutes. The Kazakh's serve, which netted her 11 aces, was key to her victory. Linette was frequently the more creative player off the ground, with her forehand redirections repeatedly catching Rybakina out.

However, the World No.59 was unable to bring her best form on the biggest points. Having clawed back an early break in the first set, she subsequently dropped it after Rybakina raised her level at the last minute, crunching her best two winners of the day on the last two points to break the Pole again. In the decider, Linette squandered early positive play by double faulting to hand Rybakina the first break point at 1-2, and thereafter falling away in a flurry of forehand miscues.

Rybakina will next face an intriguing last-eight clash with No.1 seed Iga Swiatek. It will be the first time the pair have met at pro level, though they did split two junior meetings: Swiatek was a 6-2, 6-2 victor on hard courts at Repentigny 2016, but Rybakina took her revenge 1-6, 7-6(5), 6-3 on clay in the 2017 Milan final.