Ferrer was blanked in the second set of his match before answering with a shutout of his own in defeating Adrian Mannarino 7-5, 0-6, 6-0.
Ferrer dropped serve four times -- three times in the second set. But he had three breaks in the third set when he held Mannarino to three points on serve.
Juan Monaco built a 6-2, 3-0 lead before Monfils retired. Monaco lost nine points over five service games. That includes saving three break points.
Also in the second round, Jo-Wilfried Tsonga knocked off Pere Riba 6-4, 6-2; Sergiy Stakhovsky edged by John Isner 7-5, 6-4, 7-6 (7-3); and Guillermo Garcia-Lopez raced past Thiemo de Bakker 6-2, 6-3.
The first round wrapped up Wednesday with the three seeded players on the schedule all losing.
Juan Martin del Potro continued his comeback from injury with a 6-1, 3-6, 6-3 win over 13th-seeded Mikhail Youzhny; Lu Yen-hsun topped No. 15-seeded Fernando Verdasco 7-6 (9-7), 7-5; and Florian Mayer beat Viktor Troicki 4-6, 7-5, 6-4.
Other first-round winners Wednesday were Feliciano Lopez, Marcel Granollers, Thomaz Bellucci, Gilles Simon and Kevin Anderson.
Anderson's win was worth a second-round slot versus world No. 2 Novak Djokovic, who is undefeated in 2011.