Naomi Osaka advanced to the next round of the Miami Open on Saturday without having to hit a ball when her expected Round 3 opponent, Karolina Muchova of the Czech Republic, was forced to withdraw from the tournament due to a left abdominal injury.

As a result of the walkover, Osaka is into the fourth round in Miami for the second year running. Last year, she reached the quarterfinals in her best-ever tournament result.

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Muchova and Osaka were slated to play for the third time in their careers, having split the first two meetings. While Muchova beat Osaka on clay in Madrid last spring, the Czech was contesting her first tournament since the US Open this week after being sidelined with similar abdominal problems.

In Round 2, Muchova defeated reigning US Open finalist Leylah Fernandez, while Osaka took down Angelique Kerber in a clash of Grand Slam champions.

Highlights: Muchova def. Fernandez | Osaka def. Kerber

To return to the quarterfinals, Osaka will next face the winner of the all-American match between Alison Riske and Ann Li.

Lucky loser Lucia Bronzetti of Italy also moved through to Round 4 via a walkover as Anna Kalinskaya withdrew thanks to a left arm injury. Bronzetti will next face wildcard Daria Saville of Australia. Saville also had abridged passage through to the last 16, as Katerina Siniakova retired after losing the first seven games.

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The former Top 20-ranked Australian, on the comeback trail following Achilles surgery, also reached the fourth round in Indian Wells as a qualifier, while Bronzetti, ranked World No.102, is in the midst of a breakthrough in her first WTA 1000 main draw.