MADRID, Spain - No.7 seed Kiki Bertens held off the challenge of an unseeded Jelena Ostapenko 6-4, 6-3 to move into the third round of the Mutua Madrid Open in one hour and 20 minutes.

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Last year's runner-up weathered some ferocious ball-striking from Ostapenko, but was ultimately too solid - particularly on serve and defence - for her opponent. Consistently finding her best deliveries to dig herself out of trouble, Bertens rained down 11 aces in total - and, playing with greater margin and spin than the Latvian, her strokes would rarely be the first to break down in extended rallies.

The pair had not played since Wimbledon 2016, before either player had reached the Top 20, with the Dutchwoman winning 6-3, 6-2 - avenging one previous meeting in the 2015 Sobota ITF W75 on clay, which Ostapenko had taken 6-3, 2-6, 6-3. Today, Bertens was calm and collected as, playing within herself, she controlled her side of the court in the face of Ostapenko's oscillations.

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It was the former Roland Garros champion who made the first move, pummeling a pair of backhand returns to break Bertens for 2-1. But a flurry of errors off the same wing handed it straight back, before Ostapenko missed a 0-40 opportunity and four break points in total to edge ahead again.

"You never know what ball you're going to get," Bertens said afterwards. "Well, it's always going to be fast - but you don't know if it's going to be in or out." It wasn't the former Roland Garros semifinalist's preferred matchup: "I like longer rallies, but against her you cannot do that," she admitted. Still, she felt she had played the right match tactically. "She doesn't like it when someone is so far back - and with the slices, when the ball come sback so low."

That squandered chance would prove crucial. Though the World No.29 played a relatively clean set, avoiding any of the double faults that have plagued her recently and striking some breathtaking winners, particularly forehands down the line, Bertens was repeatedly able to raise her level on big points while Ostapenko suffered several wobbles on finishing shots. Serving down 4-5, Ostapenko threw in another loose service game, and was broken to love with four errors that took her first-set total to 16.

The second set found Ostapenko diversifying her tactics in an attempt to get back into the match, finding success with sharp net attacks and even a handful of perfectly executed dropshots - one of which paved the way to an immediate break of the Bertens serve.

But once again, the 21-year-old was unable to sustain her momentum and broken back straight away, with inconsistency off the ground still hampering her - as well as the dreaded double faults creeping into her game at inopportune moments, with a third handing over another break to trail 3-5. Bertens, able to pump heavy topspin even from deep behind the baseline, was increasingly impregnable on defence, much to Ostapenko's frustration, who ended the day with 30 unforced errors to 14 winners.

But the St. Petersburg champion was also sharp in her awareness of when to take charge, even against her ultra-aggressive opponent, ending with 20 winners to a mere 10 unforced errors. The Bertens backhand in particular was a thing of beauty in the closing stages as the 27-year-old seized control to reel off 12 of the last 14 points from 3-3 in the second set, winning her the best point of the match in the final game - a pinpoint winner down the line after some dogged defensive work.

Up next for Bertens in her quest to make a third consecutive quarterfinal in Madrid will be another Latvian, No.12 seed Anastasija Sevastova - for the third year in a row in the Spanish capital. In 2017, Sevastova was a 6-3, 6-3 victor in the last eight; last year, Bertens got a 6-1, 6-4 revenge in the third round on the way to the final. Still, she's looking forward to the matchup more than today's.

"She can also be really tricky because she has the slice, the dropshot, so I cannot be as far back as I was today," Bertens reflected. "But against her, I can also play my own game more."