Second-seed Nishikori beat big-serving South African Kevin Anderson 6-4, 6-3 on centre court and will face Fernando Verdacso of Spain or young American Ernesto Escobedo in the next round.

Raonic was returning from almost a month on the sidelines due to a right leg injury and enjoyed a 6-3, 7-5 victory over Serbia's ViktorTroicki.

The Canadian was in charge of the opening set and at 3-1 up in the second, it looked all over but Troicki forced things back to level at 5-5 before Raonic got the crucial break.

Intermittent rain and high winds made it tough at times for both players but Raonic said he was glad to get back on court.

"Conditions obviously weren't ideal but I have to be very happy with just the outcome," he said adding he was still not in the best shape physically.

"But I've put in the work that I can, I have prepared the best I can for this tournament and while I'm not necessarily in the best position right now, fortunately it is a long tournament," he added.

Fifth-seed Rafael Nadal, who has never won at Miami, was in action later on Friday against Dudi Sela of Israel while Bulgarian ninth-seed Grigor Dimitrov takes on Argentina's Guido Pella.

2nd rd

Milos Raonic (CAN x3) bt Viktor Troicki (SRB) 6-3, 7-5
Philipp Kohlschreiber (GER x26) bt Taylor Fritz (USA) 7-5, 3-6, 7-6 (7/4)
Jiri Vesely (CZE) bt Albert Ramos-Vinolas (ESP x19) 7-6 (7/5), 4-6, 6-3
Jeremy Chardy (FRA) bt Marin Cilic (CRO x7) 6-4, 2-6, 6-3
Jared Donaldson (USA) bt Mischa Zverev (GER x28) 6-4, 6-4
Fabio Fognini (ITA) bt Joao Sousa (POR x30) 7-6 (10/8), 2-6, 6-3
                 
1st rd

Malek Jaziri (TUN) bt Alexandr Dolgopolov (UKR) 7-6 (7/4), retired
Thomaz Bellucci (BRA) bt Stephane Robert (FRA) 7-6 (7/5), 6-2