Murray, Li advance to fourth round at Miami
Andy Murray of Great Britain returns a shot to Feliciano Lopez of Spain during the Sony Open at the Crandon Park Tennis Center on March 23, 2014 in Key Biscayne, Florida - by Matthew Stockman
Also advancing at the hardcourt event was Chinese world number two Li Na, the reigning Australian Open champion who dispatched American Madison Keys 7-6 (7/3), 6-3.
Defending champion Murray polished his record to 9-0 over Spaniard Lopez. The Scotsman, who does much of his off-season training in Miami, improved to 21-6 in his part-time hometown.
Murray, who struggled Friday in his first match without ex-coach Ivan Lendl in his player box, had a much easier time against Lopez, winning in 73 minutes.
"It's not always that easy to feel comfortable against him because there is not loads of rhythm with the way he plays," Murray said. "But I moved well, returned well. It was obviously a more comfortable scoreline than the other day.
"I don't know how hot it was, but when we came over at like 9:30 it was already 80 Fahrenheit (23 Celsius) and it was extremely humid.
"I've played a few matches here where it's been very, very hot. But it doesn't always stay like this for a few days in a row in March. They are not easy conditions."
Murray will line up next against French 11th seed Jo-Wilfried Tsonga, who outlasted Marcos Baghdatis 4-6, 7-6 (8/6), 7-5.
Murray has won eight of their nine ATP meetings, the most recent last year on grass at Queen's.
Tsonga trailed a set and was down 5-1 in the second-set tiebreaker when he suddenly found some much-needed form, rallying to win after two and a half hours.
The Frenchman fired 16 aces and needed only one break of serve to make the winning difference.
Li spent nearly an hour surviving the first set, saving two set points on the serve of 38th-ranked Keys.
The American committed a backhand error on her first chance and double-faulted on the second before Li got the break for 5-4 in a set which eventually went into a tiebreaker.
Li won the decider on the first of four set points to seize the match momentum in front of a sparse crowd.
The Chinese number one recovered from an early break in the second set, eventually reaching 5-2.
Li then saved a pair of break points in the final game thanks to Keys' unforced errors and took victory after one hour, 41 minutes as her opponent again misfired.
"It was a pretty tough match," Li said. "She played well, big serve, big forehand, especially when she was 3-1 down and then come back 5-3 up and served for the first set.
"During that time I didn't think about too much. I say, 'OK, try to hit the ball, try to do what you have to do, and I think saving the set points at least kept me in the first set.
"This changed the match a little bit, because after that I was feeling her level drop."
Li won despite seven double faults, 26 unforced errors and just 11 winners. She broke on five of 10 chances against an opponent whom she has now beaten on two of three occasions.
Li is playing in Miami for the eighth time, reaching four quarter-finals.