Rafael Nadal and Kei Nishikori signalled their intentions at the Miami Open with straight-sets wins in Saturday's (AEDT) second-round action.

No.5 seed Nadal had little trouble in dispatching Dudi Sela, while Nishikori saw off the big-serving threat of Kevin Anderson and Milos Raonic was another comfortable winner.

Grigor Dimitrov and Marin Cilic were high-profile casualties, the Bulgarian going down to Guido Pella.

A four-time runner-up in Miami, this is one of just two ATP 1000 events that Nadal has never won, along with Paris. Indeed, nobody other than Andy Murray or Novak Djokovic has won here since 2011.

The 30-year-old sowed evidence that his renaissance remains on track with a 6-3 6-4 win over Sela, needing just a solitary break of serve in each set.

"It was difficult to find the right feelings this afternoon, but it's these kind of days where you have to just try to win. That's what I did and I am very happy with that," said Nadal, who plays Philipp Kohlschreiber next up.

Both Nishikori (2) and Raonic (3) enjoyed comfortable passage into Round 3.

Nishikori had lost his previous meeting with Anderson in Shanghai two years previously, but the Japanese was on song in Florida, preventing his opponent from carving out a single break point in a 6-4 6-3 success.

Fernando Verdasco (25) awaits Nishikori in Round 3.

Raonic was making his first appearance on tour since a leg injury forced him out of the Delray Beach Open final and subsequent tournaments in Acapulco and Indian Wells.

Viktor Troicki looked a tricky opponent, but Raonic was comfortable throughout, overcoming a slight wobble late in the second set to see out a 6-3 7-5 triumph. Local qualifier Jared Donaldson is next for Raonic, having beaten No.28 seed Mischa Zverev.

Dimitrov (9) has won only three matches since his title-winning run in Sofia in February and his slump continued here.

The Bulgarian hit 38 unforced errors to 18 winners against Argentinian Pella, who won 6-3 7-6 (7-4) to book a meeting with Nicolas Mahut.

Jeremy Chardy outlasted Cilic (7) 6-4 2-6 6-3 and there was more French success against seeded opposition as Benoit Paire beat Pablo Cuevas (21), however No.11 seed Lucas Pouille was ousted in straight sets by Donald Young.