Hubert Hurkacz, of Poland returns a shot from Arthur Rinderknech, of France, during the Miami Open tennis tournament, March 26, 2022, in Miami Gardens, Fla. (WILFREDO LEE/ AP)

Hubert Hurkacz unleashed 17 aces to topple France's Arthur Rinderknech 7-6(5) 6-2 and keep his title defense going at the Miami Open on Saturday as world number two Daniil Medvedev sent twice winner Andy Murray packing and Naomi Osaka advanced on a walkover.

Rinderknech was unable to convert his sole break point in the first set and lost the momentum altogether after the tiebreak, as the 10th-ranked Pole won the first four games of the second set of their second-round clash.

Reigning US Open champion Daniil Medvedev never faced a break and proved too nimble for three-times Grand Slam winner Andy Murray, dropping just two of his first-serve points in the second set as he won 6-4 6-2 

Reigning US Open champion Medvedev never faced a break and proved too nimble for three-times Grand Slam winner Murray, dropping just two of his first-serve points in the second set as he won 6-4 6-2. 

"Playing against Andy is never easy," said Russian Medvedev, who is on a quest to regain his number-one ranking. "Managed to serve well, and I think that was one of the keys today."

ALSO READ: Hurkacz savours breakthrough victory at Miami Open

Japan's Osaka advanced to the fourth round on a walkover after Czech Karolina Muchova withdrew following an injury she sustained during warm-ups.

The four-times Grand Slam champion will face the winner of an all-American clash between Ann Li and Alison Riske in the Grandstand later on Saturday.

Muchova's was the latest injury to mar the women's field in Miami after Garbine Muguruza and Simona Halep pulled out on Thursday.

Fritz Tested

Fresh from collecting the biggest title of his career at Indian Wells, American Taylor Fritz survived a surprise test from Kazakhstani qualifier Mikhail Kukushkin to win 6-3 5-7 6-3.

Kukushkin put up a strong defence, with eight of 11 break points saved, but struggled against his opponent's powerful serve, with the 13th-ranked Fritz launching 10 aces.

ALSO READ: Medvedev sees path back to the top through Miami Open

"There was a lot of points where I really didn't think I did anything wrong, he was just too good," Fritz, who won slightly more than three-quarters of his first-serve points, said in a televised interview.

Daniil Medvedev, of Russia, returns a shot from Andy Murray, of Britain, during the Miami Open tennis tournament,  March 26, 2022, in Miami Gardens, Fla. (WILFREDO LEE /AP)

Fritz drew a picture of the sun and the caption "x 2?" on the on-court camera after the match -- a hint that he perhaps was chasing tennis's elusive "sunshine double" of Indian Wells and Miami -- but said afterwards that the gesture was intended as a joke.

"I'm not coming here expecting to win the tournament or anything. I'm going into it with the same mentality as Indian Wells," he said. "Take it one match at a time."

Only 10 players have won back-to-back titles at the two tournaments, played in the heat of California and Florida.

Fritz's Indian Wells quarter-final opponent, Serbian Miomir Kecmanovic, dispatched seventh-seeded Canadian Felix Auger-Aliassime 6-4 6-2 and Spain's Roberto Bautista Agut moved past Pole Kamil Majchrzak 6-3 6-3.

READ MORE: Osaka cruises past Kerber to reach third round in Miami

Australian Open finalist Danielle Collins of the United States beat Vera Zvonareva 6-1 6-4, while Olympic champion Belinda Bencic eased past Britain's Heather Watson 6-4 6-1.

Swiss Bencic, who suffered early exits from Indian Wells earlier this month and Doha in February, launched five aces across the net as Watson struggled on the return and was only able to convert one of eight break points.

She next faces Aliaksandra Sasnovich of Belarus, who triumphed in their only previous meeting in the first round of the 2018 US Open.