KEY BISCAYNE, Fla. — Three days into the Sony Ericsson Open, only one American remains in the women's draw — Uzbekistan-born Varvara Lepchenko.

KEY BISCAYNE, Fla. — Three days into the Sony Ericsson Open, only one American remains in the women's draw — Uzbekistan-born Varvara Lepchenko.

Three U.S. women lost in the second round Thursday, including Bethanie Mattek-Sands, who was eliminated by No. 1-ranked Caroline Wozniacki, 6-2, 7-5. With Serena and Venus Williams sidelined for health reasons, Mattek-Sands was the highest-ranked American in the draw at No. 43.

American qualifier Jamie Hampton lost to No. 21-seeded Andrea Petkovic 6-2, 7-5, and American Melanie Oudin was beaten by No. 29 Daniela Hantuchova 6-1, 6-3.

The lone American left was the No. 82-ranked Lepchenko, who has lived in the United States since 2000 and became a citizen this year. She plays a second-round match today.

Only seven Americans made the 96-player women's field, including two wild cards and two qualifiers — a reflection of the decline in U.S. tennis fortunes in recent years.

U.S. Fed Cup captain Mary Joe Fernandez found cause for encouragement in some results at Key Biscayne. Hampton, 21, and Sloane Stephens, 18, made the draw through qualifying, and four American women won their opening match.

The situation isn't as bleak on the men's side, but there was nothing to brag about Thursday, when 18-year-olds Ryan Harrison and Jack Sock lost first-round matches.

Seeded players were in action for the first time after having byes in the opening round. No. 16 Maria Sharapova beat wild card Petra Martic 6-3, 6-2.