The top-seeded Ferrer, who has won at Valencia two of the last three years, defeated Vasek Pospisil 6-3, 6-3. Ferrer won half the points when receiving serve and finished with two breaks in each set.
Monfils, seeded No. 3, was a 6-2, 7-6 (7-5) winner over Pablo Andujar. He had six break chances in each set, cashing in two in winning the first set and one in forcing the second-set tiebreaker.
Alex Bogomolov Jr. upset No. 8-seeded Feliciano Lopez 4-6, 6-4, 7-6 (7-2) in a first-round match. Neither player had much of an advantage until Bogomolov won the first five points of the third-set tiebreaker.
In the other two first-round matches Wednesday, sixth-seeded Juan Martin del Potro topped Dmitry Tursunov 6-4, 6-1 and Marin Cilic got past Milos Raonic 6-4, 6-4.