KEY BISCAYNE, Fla. — Serena Williams has taken the first step in her bid for a record sixth Key Biscayne title.

The top-ranked Williams won her opening match Saturday at the Sony Ericsson Open, beating fellow American Alexa Glatch 6-2, 6-3.

Williams, who has won the tournament the past two years, needed barely an hour to move into the third round. Seeded players had first-round byes.

Williams is 48-5 at Key Biscayne, with one loss since 2001 — to her sister Venus.

In men's play, No. 14-seeded David Nalbandian lost to Viktor Troicki 6-1, 6-3. American Sam Querrey was eliminated by No. 32 Feliciano Lopez 6-7 (5), 7-5, 6-2.