Federer dispatched Cedrik-Marcel Stebe 6-3, 6-3 in just more than an hour in a second-round match. Federer did lose his serve once in the first set but saved the only break point he faced in the second.
Mikhail Youzhny defeated fourth-seeded Kei Nishikori, who like Federer had a first-round bye, 6-1, 6-7 (4-7), 6-3. Youzhny had at least one break in each set, including the only break by either player in the final set to advance.
Gael Monfils topped Jan Hernych 6-2, 6-3 with a strong second set in which he dropped only four points on serve, and Mischa Zverev beat Mirza Basic 7-6 (7-5), 6-3 behind three breaks in other second-round matches.
Zverev moves into Friday's quarterfinals when he'll go against Federer.
Swim Week Miami Beach 2014 [PHOTOS]