MIAMI (AFP) – Naomi Osaka reached the fourth round of the Miami Open without lifting a racquet Sunday (March 28), advancing by walkover when scheduled opponent Nina Stojanovic withdrew with a right thigh injury.

Second-ranked Osaka, the reigning US and Australian Open champion, is in the last 16 of the prestigious ATP Masters and WTA event at the Hard Rock Stadium for the first time in five appearances.

The Japanese star next faces 16th-seeded Belgian Elise Mertens, who defeated Anett Kontaveit of Estonia 6-2, 0-6, 6-2.

Osaka had looked a little rusty in her second-round opener, her first match since she lifted her fourth Grand Slam title at Melbourne in February.

An efficient serve and her ability to control the jitters saw her beat Croatian Ajla Tomljanovic 7-6 (7/3), 6-4.

With a victory in Miami, Osaka could overtake Ashleigh Barty – who won the most recent edition of the tournament in 2019 – atop the world rankings, provided the Australian doesn’t reach the final.

In other early women’s action, 29th-seeded American Jessica Pegula ousted sixth-seeded Czech Karolina Pliskova, Miami runner-up in 2019, by 6-1, 4-6, 6-4.

American John Isner, the men’s champion in 2018 and runner-up in 2019, booked a fourth-round spot with a 7-6 (7/5), 7-6 (7/5) victory over 11th-seeded Canadian Felix Auger-Aliassime.

The match was a near-carbon copy of Isner’s two-tiebreak win over Auger-Aliassime in the 2019 semi-finals.

Neither player faced a break point, Isner commanding the slight edge needed in the tiebreakers with the aid of 16 total aces to the Canadian’s 11.

The 35-year-old US veteran next faces another familiar foe in Spain’s Roberto Bautista Agut.

The seventh seed beat Germany’s Jan-Lennard Struff 4-6, 6-3, 6-2 to book a chance to avenge his 2019 quarter-final Miami loss to Isner.

Sunday’s men’s action was highlighted by top-seeded Daniil Medvedev of Russia, who battled for a place in the last 16 against 86th-ranked Australian Alexei Popyrin.

Medvedev owns a 2-0 career record against the 21-year-old Aussie, who captured his first ATP title in Singapore last month.

“He’s a great player,” Medvedev said of his sometime practice partner Popyrin. “Great strokes, great serve. Solid baseline player, but he can go to the net, hit winners from all corners of the court.

“It’s going to be a tough match,” added Medvedev, who followed a runner-up finish to Novak Djokovic at the Australian Open in February with his 10th ATP title at Marseille to rise to No. 2 in the world behind the Serbian star.

Last modified: March 29, 2021