World No 2 Daniil Medvedev proved too strong for Andy Murray in the second round of the Miami Open on Saturday, while defending champion Hubert Hurkacz kept alive his defence with a straight sets win over Arthur Rinderknech, and Naomi Osaka advanced on a walkover.
Reigning US Open champion Medvedev never faced a break and proved too nimble for three-time 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."
Hurkacz unleashed 17 aces to topple France's Rinderknech 7-6, 6-2. 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.
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-time Grand Slam champion will next face Alison Riske, who defeated Ann Li 6-2, 3-6, 6-3 in an all-American clash.
Muchova's was the latest injury to mar the women's field in Miami after Garbine Muguruza and Simona Halep pulled out on Thursday.
World No 5 Stefanos Tsitsipas held off strong resistance from American qualifier JJ Wolf and won 6-4, 6-7, 6-1. The Greek, who hit 37 winners, will next face Alex de Minaur who defeated fellow Australian Jordan Thompson 6-2, 6-3.
"He's a fighter," Tsitsipas said of De Minaur. "I really hope to bring out the same kind of level that I brought in the third set and maintain that throughout the match."
Spain's 18-year-old Carlos Alcaraz secured his maiden win at the Miami event with a comfortable 6-3, 6-2 victory against Marton Fucsovics of Hungary.
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.
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."
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.
Canadian Denis Shapovalov lost 6-3, 6-4 to Lloyd Harris of South Africa, American Jenson Brooksby defeated Nikoloz Basilashvili 6-3, 6-1 and Marin Cilic beat Alexei Popyrin 6-0, 6-3.
Karen Khachanov lost 6-4, 3-6, 7-6 to Tommy Paul, Daniel Evans suffered a 3-6, 6-4, 6-3 defeat by qualifier Yoshihito Nishioka, and Cristian Garin was knocked out 7-6, 6-2 by Pedro Martinez.
Aslan Karatsev won 7-5, 6-2 against Ugo Humbert and Sebastian Korda beat Albert Ramos-Vinolas 4-6 7-6, 6-3.
In the women's field, 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.
