Petrova, 11th in the world rankings, got by world No. 150 Dinah Pfizenmaier 7-6 (7-2), 6-4. Petrova managed the only break of the second set, saving the two break points she faced. She ended up winning 71 percent of the points on serve.
Qualifier Mirjana Lucic-Baroni, 103rd in the rankings, improved to 3-0 in her career against world No. 29 Elena Vesnina with a 6-0, 6-4 romp. Lucic-Baroni allowed Vesnina just 22 points in the first set and won 56 percent of the points overall in the second.
Swim Week Miami Beach 2014 [PHOTOS]