Before each day's play at the 2021 Miami Open, we'll preview three matches to look out for.
 Ashleigh Barty vs.  Aryna Sabalenka
Both had one foot out the door in their openers. Yet each found a way to reach this projected quarterfinal encounter. Sabalenka has strengthened with each win after wiping away two match points against Tsvetana Pironkova. Her latest win, a 6-1, 6-2 demolition of No. 19 seed Marketa Vondrousova, saw Sabalenka advance without getting broken. Going toe-to-toe on this front with the Australian, whose serve repertoire is one of the best in the business, will be critical to replicating her prior successes.
Barty won the pair’s first meeting in the first round of the 2018 Australian Open, but since then, has dropped three WTA clashes to the Belarusian—all on Chinese soil (Barty won a Billie Jean King Cup semifinal encounter in 2019). While she opted out of tournament play for nearly a year, Barty has confidently returned to win 11 of her 13 matches, and has handled the occasion as defending champion well at her first international event in 13 months. On Monday, she prevailed in three over Sabalenka’s countrywoman Victoria Azarenka—a battle that reinforced how influential Barty’s backhand slice can be in disrupting baseline exchanges with imposing ball-strikers.
 Jannik Sinner vs. Emil Ruusuvuori
Still just 19, Sinner comes in as the more experienced player on tour, with 76 matches to 37. Yet, both are relative newcomers when it comes to ATP Masters 1000 competition, as this marks just Sinner’s fourth appearance and Ruusuvuori’s second. With No. 3 seed Alexander Zverev out, thanks the Finn’s impressive turnaround in round two, this is a golden opportunity for each rising star to scale new heights and expand their fan bases.
For the second time this year, Sinner outlasted Karen Khachanov in three nail-biting sets when he rallied from a set down Sunday. “I’m a little bit red, like my hair,” the Italian said on Tennis Channel after proving adept at handling the tournament’s blistering conditions. For Ruusuvuori, he achieved one of the hardest tasks in sport—consolidating an upset—by overcoming Mikael Ymer. Sinner possesses a tad more weight of shot, but Ruusuvouri brings plenty of excellence to the table in the groundstroke department.
 Daniil Medvedev vs. Frances Tiafoe
We’ll find out just how important the post-match recovery process is when Medvedev takes the court. In our latest look at the world No. 2, Medvedev appeared all but spent when his “legs were not following me.” Alexei Popyrin wasn’t able to capitalize on the Russian’s cramping, and Medvedev lived another day with his get-in-and-get-out point mentality.
What is working in Medvedev’s favor? He’s won eight of nine sets played against Tiafoe, which includes relinquishing just five games in the round of 16 at last year’s US Open. How about Tiafoe’s advantage? It might just be as simple as having the clutch hand. In all three of his wins over the past week, Tiafoe has stormed back from a set down, taking out No. 19 seed Dan Evans and No. 16 seed Dusan Lajovic along the way. Getting ahead early when stepping to the line will be imperative, as the American has been broken 21 times across his three defeats to the two-time major finalist.