Monfils, the No. 1 seed, was hampered in the third set by a left knee injury, and lost, 3-6, 6-1, 7-6 (7-1), to third-seeded Feliciano Lopez of Spain, while Spain's Ferrer, the second seed, was a 7-5, 6-4 victim of Monfils' French countryman, eighth-seeded Stephane Robert.
"I realized after the first break in the second set that he was injured because he was not running during the points and he was trying to change the game plan by coming to the net," Lopez said about the decisive third set against Monfils. "I just had to think about my game."
Sunday, Robert will compete in a final for the first time, and Lopez tries for his second career title.
The winner collects $75,700.
Ray Liotta sues skin care company over use of likeness
Boston schools pull out free condoms over wrapping complaints