Monaco dropped just eight points on serve in a 6-4, 6-2 win over Pere Riba in the clay-court tournament. He didn't face a break-point situation in the match.
Eighth-seeded Pablo Cuevas earned a quarterfinal berth against Monaco with a 7-5, 6-4 victory over Peter Luczak. Unlike Monaco, Cuevas was often on defense, saving seven of eight break-point chances forced by Luczak.
Simon Greul advanced out of the second round at the expense of No. 6-seeded Daniel Koellerer, whom Greul beat 6-1, 6-4. Also, Maximo Gonzalez defeated Oscar Hernandez 7-5, 3-, 6-1. Gonzalez and Greul will play each other in the quarterfinals Friday.
Monaco draws Cuevas for his quarterfinal opponent while No. 5-seeded Albert Montanes meets Fabio Fognini and Ruben Ramirez Hidalgo plays Santiago Ventura in the other matches Friday.
The tournament finals are scheduled for Sunday when the champion will collect $105,000.
Swim Week Miami Beach 2014 [PHOTOS]