ACAPULCO, Mexico — Top-seeded Fernando Verdasco was knocked out of the quarterfinals of the Mexican Open 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.

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.