(REUTERS) - Croatian second seed Marin Cilic survived a tough examination by Canadian Vasek Pospisil to reach the Miami Open fourth round with a 7-5 7-6(4) victory after nearly two hours on Sunday (March 25).

The big-hitting Cilic fired six aces and saved all three break points he faced, but the 77th-ranked Pospisil made it more difficult than the Croat probably expected.

Trailing 5-6 0-40 in the second set, the Canadian saved three consecutive match points and hit a running forehand pass to cap a 33-shot rally before Cilic claimed victory in the tiebreak.

With Swiss top seed Roger Federer out, the tall Cilic will be eyeing his first title of the year and 18th of his career.

Indian Wells champion Juan Martin del Potro of Argentina and Bulgarian third seed Grigor Dimitrov were playing later on Sunday.

Early winners included South Korean Chung Hyeon and Serbian Filip Krajinovic.

Chung, the 19th seed, needed just 62 minutes to dispatch American qualifier Michael Mmoh 6-1 6-1, winning 84 percent of his first serve points.

The highest-ranked player from Asia at number 23, Chung has not dropped a set so far in the tournament.

He will next face Portugal's Joao Sousa, who outlasted American Jared Donaldson 1-6 6-3 6-4.

Krajinovic defeated Frenchman Benoit Paire 6-3 6-3.