The Argentine, seeking his first title in three years, will face second-seeded Gael Monfils of France in the semi-finals.
Monfils benefited from the retirement of Argentine Leonardo Mayer when leading 6-3, 6-7 (4/7), 4-1.
Nicolas Almagro continued his men’s title defense with a 6-2, 7-6 (7/2) win over Spanish compatriot Daniel Gimeno-Traver and will meet Martin Vassallo Arguello of Argentina for a place in the final.
Vassallo Arguello beat qualifier Dan Koellerer of Austria 6-3, 7-6 (7/6) for his first semi-final in two years.
In the women’s draw, Williams overcame a mid-match stumble to put away Hungarian qualifier Agnes Szavay 6-2, 5-7, 6-1.
Second-seeded Pennetta maintained her bid for a sixth successive final in Acapulco by overcoming Petra Cetkovska of the Czech Republic 2-6, 6-3, 6-0. Second-seeded Pennetta set up a rematch of the 2004 final with another Czech, Iveta Benesova, who beat Mathilde Johansson of France 6-1, 6-3.
RSS