It'll be the current World No.1 versus a former World No.1 for the right to advance to the quarterfinals at the Miami Open.

Three-time champion Victoria Azarenka will square off against top seed Ashleigh Barty in the round of 16 after overcoming another major champion, Angelique Kerber, in Saturday's third round, 7-5, 6-2. 

Azarenka rallied from a 4-1 deficit in the first set to eventually beat Kerber for the ninth time in 10 career meetings, six of which have come in straight sets.

"It's never like an easy match, so it's always a really quality match. I think that our games do match pretty well," Azarenka assessed of the pair's longtime rivalry, which dates back to 2012.

"She's a counterattacking player. She's great in defense. I do use that part of my game as well sometimes, so it does match to have a lot of like long rallies and tough games. I felt that I have always been managing to take my chances in the match, and I know no matter what it's going to be really hard, so I prepare to play against Angelique.

"When things weren't really working out in the beginning for me, I felt that I was looking for the right approach, trying to find my rhythm, so I think that's what I'm the most proud of today.

"Then the game started to pick up. My rhythm started to pick up. My movement started to pick up. I felt like it came first from my approach and my mentality."

2021 Miami Highlights: Azarenka books Round of 16 berth after Kerber win

Read more: Barty moves past Ostapenko, Konjuh upsets Swiatek in Miami

The No.14 seed was playing her first match of the tournament after receiving a second-round walkover from Laura Siegemund, while Kerber had recorded a double-bagel victory over Mexico's Renata Zarazua in the second round. 

After she lost four straight games after breaking serve at love to begin the match, Azarenka's comeback effort gained steam thanks to a marathon seventh game.

Unable to break in the fifth game despite having opportunities at 15-40, the Belarusian later denied Kerber three opportunities to extend her lead to 5-2 before getting the opener back on serve.

Azarenka ultimately won six of the last seven games to take a one-set lead, with Kerber only moving ahead 5-4 after saving break point, and broke serve three times in the second set to seal victory.

Azarenka and Barty, who partnered to reach the 2019 US Open final in doubles, have split two singles meetings in straight sets. Azarenka was victorious in Tokyo in 2018, while Barty's victory helped lead Australia to the Billie Jean King Cup in 2019.

"She's a very talented player. I always have been a huge fan of her game and the way she plays, the way she handles herself. She has a lot of variety. She has pretty much every single shot there is. [It's] going to be a great match."

- Victoria Azarenka on facing Ashleigh Barty

Also advancing to the fourth round was Azarenka's compatriot Aryna Sabalenka, as the No.7 seed overcame No.32 seed Veronika Kudermetova in another tight two-setter, 7-6(4), 6-4. 

After cruising past the Russian with the loss of just four games to win her ninth career WTA singles title in Abu Dhabi in January, Sabalenka did not have Saturday's rematch all her own way.

A break down for much of the opener, Sabalenka saved set point in the 10th game of the set before winning the tiebreak, and earned the decisive break of serve in the ninth game of the second after neither woman was challenged on serve in the first eight games. 

"It definitely was a battle and she played really well. Her serve was really unbelievable today and I couldn't do anything against her serve. I think was just lucky that I got that break," Sabalenka said on-court after the match.

"I kept telling myself to play aggressive, keep going and put pressure on her. I just kept saying that to myself and it worked really well today."

Sabalenka will next face No.19 seed Marketa Vondrousova for a spot in the last eight.

aryna sabalenka
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60% Win 3
- Matches Played
40% Win 2
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Czech lefty Vondrousova made her way into the round of 16 by overcoming 11th-seeded Belinda Bencic, 4-6, 6-4, 6-4.

"It was such a tough match," Vondrousova said on-court, after her win. "[I'm] friends with Belinda, so it was kind of tough, and I’m just happy to be through. I served well, and I think it was a great match."

Vondrousova, a quarterfinalist at the most recent Miami Open in 2019, claimed her first Top 20 victory of the season as she charged back against Bencic in nearly two-and-a-half hours of engaging play.

Vondrousova held 12 break points in the match, converting four of those chances to eke out the win. Vondrousova also had 29 winners to 26 unforced errors, while Bencic had 33 winners but was undone by 45 unforced errors.

Two evenly matched sets opened the clash and it was only a late break of serve in each frame that separated the two combatants, facing off for the first time. Bencic closing out the opening set with a forehand winner off a dropshot was mirrored by the successful dropshot Vondrousova executed to claim the second set.

Another fascinating tussle occurred in the decider, where there were no break points through 4-4. But a Vondrousova crosscourt backhand winner queued up the first chance of the set, and she took the 5-4 lead with a break after a rally ended with a netted forehand by Bencic.

Serving for the match, it was Vondrousova's turn to suddenly face break point after another of her dropshots went awry, but the Czech powered her way out of trouble to reach match point. There, Vondrousova slammed an ace to advance into her meeting with Sabalenka.

"[Sabalenka is] a great player, she has such amazing achievements," Vondrousova said. "She’s won so many tournaments and I think she’s playing so well, so I’m just going to rest, and I can’t wait to be back."

Another Czech left-hander closed out the day, as No.9 seed Petra Kvitova dispatched former Miami champion Johanna Konta, 6-1, 6-2.

17th-seeded Konta won the biggest title of her career to date at the 2017 Miami Open, but she could not sink her teeth into this nightcap against Kvitova as the two-time Wimbledon champion zipped to victory in just under an hour.

Kvitova did not face a break point all night as she slammed 19 winners to notch her second breezy win of the event. Kvitova has only dropped seven games in her first two matches during the fortnight, and has now reached the Miami round of 16 for the fourth time in her career.

Excellent volleys coupled with strong returning gave Kvitova a break in the second game of the match, and she cruised to the one-set lead from there, with just four unforced errors in the opener.

Konta could not turn the momentum on her side as the second set started, double-faulting to drop serve in the first game of the frame. Kvitova eased to victory from there, improving her head-to-head record against Konta to 4-2 (3-0 on hardcourts).

Kvitova will now be part of a battle between Top 10 seeds in the round of 16 as she next faces 5th-seeded Elina Svitolina. Kvitova has won seven of her nine prior meetings with Svitolina.