Cilic was on the court for nearly 2 hours before finishing off a 6-4, 7-6 (7-1) win over Sergei Bubka. Cilic started slowly, landing just 40 percent of his first serves in the first set, but was able to get two breaks to take the set.
He had more success in the second set, saving the only break point he faced. Bubka fought off five break-point chances before Cilic was able to pull away in the tiebreaker.
Seventh-seeded Alex Bogomolov Jr. needed just 66 minutes to get by Igor Kunitsyn 6-3, 6-1. Bogomolov dropped 12 points over eight service games and had four breaks in the match.
No. 8-seeded Dmitry Tursunov capped the day with a 7-5, 6-3 win over Teymuraz Gabashvili. He had five breaks in Gabashvili's 11 service games.
Lukas Rosol defeated Ernests Gulbis 6-3, 6-4; Julien Benneteau routed Pere Riba 6-2, 6-1 in 56 minutes; and Somdev Devvarman topped Karol Beck 6-2, 6-3. Also Tuesday Dusan Lajovic got by Jeremy Chardy 6-4, 6-4 and Michael Berrer beat Mikhail Kukushkin 6-1, 4-6, 6-4.
Swim Week Miami Beach 2014 [PHOTOS]