ACAPULCO, Mexico(AP) Top-seeded Fernando Verdasco was knocked out of the quarterfinals of the Mexican Open on Thursday by Juan Monaco, and women's No. 1 seed Venus Williams fought back from 1-5 down in the final set to survive.

Monaco of Argentina beat top-seeded Verdasco of Spain 7-5, 6-3.

Williams had a harder-than-expected struggle against Spanish qualifier Laura Pous Tio, finally winning 4-6, 6-3, 7-5. Pous Tios is ranked No. 399 and Williams is No. 5.

Verdasco, who defeated Andy Roddick in an ATP final two weeks ago in San Jose, California, said he had not adjusted to clay after not having played on the surface in seven months.

I played better than the first two days here, but I still didn't have the level I needed to beat a solid player on clay - and one who played well like Juan,'' Verdasco said.There is not much more to say.''

Monaco credited his serve.

``I have beaten a top 10 guy who has been playing well for several years. But I can't think about it too much because tomorrow I have to start from zero.''

Fernando Gonzalez of Chile rallied to beat Eduardo Schwank of Argentina 3-6, 6-3, 7-5, while third-seeded David Ferrer of Spain defeated Uruguay's Pablo Cuevas 7-5, 6-4.

``When I won the first set, the second was easier and I played with more confidence and was more aggressive,'' he said.

In a late match, two-time defending champion Nicolas Almagro of Spain faced countryman and No. 4 Juan Carlos Ferrero.

Williams got herself into several holes with loose ground strokes and showed this is her first tournament of the season on clay - her weakest surface.

``I just thought I'm not going to give it to her. That's the first thing I thought,'' Williams said.

Williams, who won here last year, was cheered on by thousands of fans.

I really have never had that kind of support, ever in my life,'' Williams added.Never, never at home, never anywhere. ... Never Fed Cup, never even the Olympics. ... It was just really amazing. I thought, Ok, yeah, I can do this.''

``If I never experience that again, I can remember today.''

In other women's quarterfinals, Polona Hercog of Slovenia advanced to the semifinals over second-seeded Agnes Szavay of Hungary. Hercog won the first set 6-4 and Szavay was up 1-0 in the second before she retired with a left thigh injury.

In the two other quarterfinals, No. 5 Carla Suarez Navarro of Spain defeated No. 3 Gisela Dulko of Argentina 6-1, 7-6 (4), and Edina Gallovits of Romania won over Sharon Fichman of Canada, 7-5, 6-2.

Suarez Navarro started strongly but then struggled in the 90-degree, mid-day heat to hang on against the Argentine.

``In the second set I could have played a little better, but I'm happy with the victory,'' Suarez Navarro said.