World No.1 Novak Djokovic moved closer to a possible fourth Miami Open trophy on Monday by defeating Belgium’s Steve Darcis 6-0 7-5 to reach the fourth round.

Defending champion Djokovic, seeking his third March hardcourt double of Indian Wells and Miami in the same year, fired five aces and broke Darcis five times in the 98-minute outing.

Djokovic will next play Ukraine’s Alexandr Dolgopolov, who ousted Brazil’s Thomaz Bellucci 7-5 6-4.

Australian Open winner Djokovic wrapped up victory with a break in the final game to earn his 21st victory of the season as he pursues his third title of the year.

Japan’s Kei Nishikori took just over an hour to defeat Serbia’s Viktor Troicki 6-2 6-2 to also secure a fourth-round berth.

Asia’s top player — who reached the semi-finals in Miami last year — could not fault his performance.

“I played good tennis today, almost perfect. I’m excited that I’m playing good here. Maybe he was hurting a little bit, but still I was giving him a lot of pressure with my return,” Nishikori said.

“It was a great match today. I felt great on the court, so very happy to win.”

Nishikori will next face Belgium’s David Goffin, who beat Poland’s Jerzy Janowicz 6-4 6-3.

Alexandr Dolgopolov of Ukraine also reached the fourth rond with a 7-5 6-4 win over Brazil’s Thomaz Bellucci.