Miami Open: Defending champion Hubert Hurkacz advances, Daniil Medvedev stops Andy Murray, Naomi Osaka gets walkover

Hubert Hurkacz unleashed 17 aces to topple France's Arthur Rinderknech 7-6(5) 6-2 and keep his title defence 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 U.S. 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." Japan's Naomi 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 TESTEDFresh 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. "There was a lot of points where I really didn't think I did anything wrong, he was