The Omnium Banque Nationale quarterfinals will see the fourth edition of the big-name all-Belarusian rivalry between Aryna Sabalenka, after the countrywomen won their third round matches in contrasting fashion.

No.1 seed Aryna Sabalenka became the first player into the last eight of the Omnium Banque Nationale with a 6-1, 6-3 defeat of wildcard Rebecca Marino.

The result marks Sabalenka's eighth quarterfinal run of the year, and first in Montreal. Having battled for two hours and 25 minutes to overcome Sloane Stephens less than 24 hours previously, the Belarusian bounced back to race past Marino in only 59 minutes.

She was followed on Centre Court by No.8 seed Azarenka, who needed two hours and 34 minutes to triumph in a nailbiter over No.11 seed Maria Sakkari 6-4, 3-6, 7-6(2). Three-time Montreal/Toronto semifinalist Azarenka needed to overturn a 2-4 deficit in the third set to reach her fifth quarterfinal of 2021.

Given both players' power-centric approach to the game, the contest was unsurprisingly decided by the quality of their serving. World No.220 Marino had upset two Top 50 players in Madison Keys and Paula Badosa to reach this stage, but was unable to find the same form at first. A flurry of unforced errors saw her drop her opening service game to love; landing only 39% of her first serves in the first set, the Canadian did not get on the board until the sixth game.

Sabalenka's service stats ostensibly indicate inconsistency, with six aces outweighed by seven double faults, but it was when they came that was important. The double faults rarely got the Wimbledon semifinalist into scoreboard trouble, mostly occurring when she already had a lead in a game; by contrast, she saved all five break points she faced with either aces or service winners.

Read more: Healthy mentally and physically, Marino showing strong form in Montreal

Marino, the former World No.38 who is returning to the sport after retiring in 2013 due to depression, delivered a better serving performance in the second set, raising her first serve percentage to 59%. But at 3-3, Sabalenka gave herself an opening with one of her best forehand winners of the day, and Marino responded with a forehand over the baseline to drop serve.

Marino's best shots had come in flurries - three heavy returns in a row in the third game of the first set, three aces in the first game of the second. But serving to stay in the match, she coughed up consecutive double faults. Sabalenka made no mistake in taking advantage, sealing her second match point with a backhand winner.

Azarenka survives Sakkari in 3rd-set tiebreak: Montreal Highlights

2021 Montreal

Azarenka holds nerve to win nailbiter

Azarenka's only previous encounter with Sakkari had been a straightforward 6-1, 6-3 defeat in last year's Ostrava semifinals - a match which, coincidentally, also set up a clash against Sabalenka.

It was very different this time round, with the former World No.1 pushed to the limit by Sakkari, whose full commitment to more aggressive tactics has been evident in 2021. The Greek finished with 35 winners to 44 unforced errors, compared to Azarenka's 17 winners and 27 unforced errors.

Throughout the match, Sakkari walked a tightrope of keeping Azarenka on the back foot while battling her own inconsistency. A forehand winner gained her an immediate break of serve, but errors off that wing saw the 26-year-old broken at 3-3 and come up short down set point.

Sakkari's subpar 46% first serve percentage had also hampered her in the first set, but raising it to 65% in the second enabled her to turn the match around. As in the opener, she was unable to hold on to an early break - but this time, Sakkari responded with a mid-set purple patch in which she fired a series of down-the-line winners past Azarenka. The scintillating form continued into the decider, which saw Sakkari save four break points in grinding out her first two service games en route to a 4-2 lead.

To this point, Azarenka had opted for a steady strategy. Just five of her 17 winners had come in the first two sets. But with her back to the wall, the two-time Australian Open champion rose to the occasion. She came up with her finest shots in the home stretch of the match, including a magnificent reflex pass to bring up a crucial break-back point for 4-4 - converted as Sakkari committed her seventh of eight double faults.

aryna sabalenka
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75% Win 3
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25% Win 1
victoria azarenka

The set would head inexorably towards a deciding tiebreak, and once there it was Sakkari whose game proved less reliable. The Roland Garros semifinalist opened with three unforced errors and a double fault, and the 0-4 hole was too deep to overcome.

Friday's quarterfinal will be the fourth meeting between Azarenka and Sabalenka. Sabalenka leads the head-to-head 2-1, having scored wins at the 2019 US Open and the 2020 Ostrava final. In between, Azarenka triumphed at the 2020 US Open en route to her fifth major final.