No.4 seed Elena Rybakina held firm in blustery conditions to reach her second consecutive Miami Open quarterfinal, defeating No.17 seed Madison Keys 6-3, 7-5 in 1 hour and 24 minutes.

The result was the 2023 finalist's first straight-sets win of the fortnight. She had needed three sets to get past both Clara Tauson and Taylor Townsend in her previous two rounds.

Rybakina leveled her head-to-head record at two wins apiece against Keys, who was bidding to return to the last eight of Miami for the first time since 2016. All three of their previous meetings had occurred in 2022, with Keys winning on the clay of Roland Garros and the outdoor hard courts of Cincinnati, but Rybakina claiming her first victory of the series indoors in Ostrava.

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The Kazakhstani will next face No.8 seed Maria Sakkari, who advanced to her second Miami Open quarterfinal via walkover. No.22 seed Anna Kalinskaya was forced to withdraw ahead of their fourth-round match due to a right thigh injury.

"I'm so sorry, I was really looking forward to playing today," Kalinskaya said in a statement. "But unfortunately, my health doesn’t allow me. Thank you for your support."

Both Sakkari and Kalinskaya have been WTA 1000 finalists this season. Kalinskaya was runner-up in Dubai to Jasmine Paolini; Sakkari reached her fourth WTA 1000 final last week in Indian Wells, falling to Iga Swiatek. The Greek player's previous best Miami performance was a semifinal run in 2021, when she defeated Naomi Osaka before losing to Bianca Andreescu. 

Rybakina holds a 2-1 record against Sakkari overall. Rybakina has won both of their three-setters, triumphing 3-6, 7-5, 6-1 in the 2020 St. Petersburg semifinals and 6-0, 6-7(4), 7-6(2) in the 2023 WTA Finals Cancun group stage. Sakkari captured her sole win 7-5, 6-4 in the 2022 Indian Wells quarterfinals.

How Rybakina defeated Keys: Unsurprisingly for a match between two formidable servers, the key numbers were the efficiency of both players' deliveries. Rybakina was superior on both first serve -- behind which she won 81% of the points compared to Keys's 62% -- and second, where she captured 50% of the points compared to 44%.

Rybakina did not face a break point in the first set, and though she missed her first four opportunities to capture the Keys serve across two games, she broke through at 5-3 as the American sent a backhand long.

Indeed, Rybakina only faced break point in one game overall. She led 3-1 in the second set, but some fine returning and net attacks from Keys enabled the former US Open finalist to get back on serve. But Rybakina held firm through the remainder of a tight set and pounced again to break at 5-5.

Putintseva maintains strong form: Rybakina's Kazakhstani compatriot Yulia Putintseva also continued a stellar month, coming from 4-2 down in the second set to defeat No.32 seed Anhelina Kalinina 6-4, 7-6(5). The World No.79, who also saved two set points in the second set, deployed deft touch and careful point construction to handle the windy conditions.

Putintseva, who is fresh off a fourth-round run at Indian Wells, advanced to her sixth career quarterfinal at WTA 1000 level or above following Roland Garros 2016 and 2018, the US Open 2020, Rome 2020 and Toronto 2022.

The five best cat-and-mouse points from Putintseva's Miami win vs. Kalinina

Miami expert Azarenka advances: To make her first WTA 1000 semifinal, Putintseva will have to get past three-time Miami Open champion Victoria Azarenka in the quarterfinals. No.27 seed Azarenka took down No.24 seed Katie Boulter 7-5, 6-1 in 1 hour and 47 minutes on Monday.

Highlights: Azarenka def. Boulter

In the opening set, Azarenka missed three set points at 5-2 and two more at 5-4, as last month's San Diego champion Boulter made a comeback. However, at 6-5, Azarenka converted her sixth set point to take the one-set lead, then romped through the second set.

Former World No.1 Azarenka is into the Miami quarterfinals for the sixth time, but it is her first trip that deep at this event since a semifinal run in 2018. Azarenka won this title in 2009, 2011 and 2016; in 2016, she pulled off the Sunshine Double by winning Indian Wells and Miami back-to-back.

Azarenka leads Putintseva 2-0 in their head-to-head, posting down-to-the wire wins at the 2021 Grampians Trophy (in Melbourne) and 2022 Doha.