Australian Open champion Jannik Sinner is through to the Miami Open quarter-finals, while Daniil Medvedev also progressed with a straight-set win.
The talented 22-year-old Italian, who triumphed in his first major final in Melbourne in January, beat Australian Christopher O'Connell 6-4 6-3.
The world number three will play Czech Tomas Machac for a semi-final place.
Fourth-ranked Russian Medvedev defeated German Dominik Koepfer 7-6 (7-5) 6-0 to set up a meeting with Nicolas Jarry.
Chilean Jarry, the 22nd seed, stunned Norway's world number eight Casper Ruud 7-6 (7-3) 6-3.
Sinner fell a break of serve behind against the 66th-ranked O'Connell but he reeled off four successive games to turn around the first set before striking early in the second on his way to clinching an ultimately straightforward victory.