Rafael Nadal, a No. 2 seed and finalist at Miami in 2005, 2008 and 2011, reached the Sony Ericsson Open quarterfinals for the sixth consecutive year by knocking out No. 16 seed Kei Nishikori of Japan 6-4, 6-4.
In his biggest challenge thus far in the tournament, 25-year-old Nadal struggled to find his form in the opening games and Nishikori put himself in position to take control of the match. But the Japanese player failed to convert on six of seven break point opportunities in the opening three games of the first set and would have only one another break point chance for the remainder of the match.
Nadal broke Nishikori with a forehand smash to wrap up the first set and then was able to convert two more break point opportunities in the second set.
Nadal, who has yet to drop a set in three matches of this tournament, will face the No. 6 seed Jo-Wilfried Tsonga of France, who beat Germany's Florian Mayer.
Javea's David Ferrer is also through to the quarter-finals having dismissed 11th-seeded Juan Martin del Potro 6-3, 6-3 in night-session action. Ferrer won 77% of his first serve points, and broke the Argentine three times to wrap up the win in one hour and 36 minutes.
"I played very well tonight. I played very consistent, very solid," said Ferrer. "A good performance and maybe my best match this year... My best results are on hard courts. I like this surface. I like the fans here in Miami. I like this tournament."
Del Potro dropped his second straight meeting to Ferrer, after falling in five sets to the World No. 5 in a Davis Cup Final rubber last December.
Ferrer now faces the No. 1 seed Novak Djokovic, who has a 7-5 head to head lead over him. Ferrer most recently bowed out to the 24-year-old Serb in the Australian Open quarter-finals. Ferrer's last victory over the top seed came in the round-robin stage of the 2011 Barclays ATP World Tour Finals.
"It's going to be difficult to beat Novak. But I will try to do my best," Ferrer said. I have to play very solid. I need [a] good percentage with my first serve."
Spain's third highest ranked player, Nicolás Almagro, was despatched by the top-ranked American and No. 8 seed Mardy Fish 6-3, 6-7 (2), 6-3. After picking up his game to force the second-set tie-break and then the deciding set, the match momentum appeared to have swung Almagro's way. He failed to take his numerous break-point opportunities, however and Fish pounced at the first opportunity to seal the victory.