KEY BISCAYNE, Fla. — Serena Williams' reign on Key Biscayne was ended by Victoria Azarenka.

The 19-year-old from Belarus won 6-3, 6-1 Saturday in the final of the Sony Ericsson Open, spoiling Williams' bid for a record sixth Key Biscayne title.

The top-ranked Williams played with her left thigh taped and struggled to move to her left. She was also hampered by erratic strokes and had trouble putting Azarenka's 90-mph serves into play.

Williams led 3-2 before Azarenka won five consecutive games to take control. The teenager also won the final five games and closed out the biggest win of her career when Williams sailed a backhand long.

For Azarenka it was a big improvement on their match in the fourth round at the Australian Open in January, when she became sick to her stomach beforehand and lost.

Azarenka, who won her first tour title three months ago at Brisbane, improved to 23-2 this year. She grew up in Minsk and befriended NHL goaltender Nikolai Khabibulin, who invited her to the United States to practice. She moved in 2005 to Scottsdale, Ariz., and trains there.

Williams' record at Key Biscayne since 2001 fell to 38-2, with the only other loss to her sister Venus. Despite the defeat, she'll retain the No. 1 ranking for a 10th consecutive week next week, while Azarenka will climb to a career-best No. 8.

Azarenka won $700,000, more than the men's first prize of $605,500. The two tours offer the same total prize money but distribute it differently. Williams received $350,000.