Lopez, the No. 6 seed, defeated Mikhail Kukushkin 6-4, 6-4 behind a 13-ace attack. Lopez claimed the early lead by taking the only break of the first set. He lost both break points he faced in the second set but answered with three breaks of his own to advance.
Chardy, seeded eighth, had 10 aces in a 7-6 (7-4), 7-5 in over Adrian Mannarino. Chardy put the match away with a late second-set break, giving him three in the set and four on the day.
Qualifiers Marius Copil and Yuichi Sugita were on the court for just short of three hours before Copil finished off a 7-6 (7-5), 6-7 (2-7), 7-6 (9-7) victory in which neither player had his serve broken.
Copil had 31 aces and saved the two break points Sugita managed. Sugita, who won two more points -- 128-126 -- in the match than Copil, fought off eight break chances.
Also Tuesday, Nicolas Mahut topped Igor Sijsling 3-6, 6-4, 6-4; Lleyton Hewitt defeated Thanasi Kokkinakis 6-3, 7-5; Matthew Ebden took out Alex Kuznetsov 6-3, 6-4; and Samuel Groth advanced over Ryan Harrison 7-6 (7-3), 7-6 (7-2).
Swim Week Miami Beach 2014 [PHOTOS]