Rising from her chair following the final changeover, Serena Williams glanced at her skirt and brushed away some lint, trying to look good in defeat.

It wasn't easy. A sore leg and erratic strokes were too much to overcome, and the top-ranked Williams was upset 6-3, 6-1 Saturday by 19-year-old Victoria Azarenka in the final of the Sony Ericsson Open.

Williams said her left thigh began bothering her in the quarterfinals, and she also was bothered by a sprained ankle.

"It was a little difficult moving to the left and a little bit to the right," she said. With a chuckle, she added, "A little forward was also difficult."

The loss ended Williams' reign on Key Biscayne. She was bidding for a record sixth women's title and her third in a row. Instead, she fell to 38-2 in the tournament since 2001, with the only other loss to her sister Venus.

"I'm not that bummed, because I feel like there's next year," Williams said. "And then there's the year after and the year after."

The result heralded the emergence of Azarenka of Belarus, who trains in Scottsdale, Ariz., and will improve to a career-high No. 8 next week.

Williams played with her thigh taped, and even when she wasn't on the move, her strokes lacked consistency. She served poorly and had trouble putting Azarenka's 90 mph serves into play.

Williams limped at times and said she considered pulling out before the match.

"I don't like to not play," she said. "I gave the effort that I could give today. That's all I could give."

Azarenka quickly realized Williams wasn't 100 percent and took advantage with pinpoint strokes to the corners.

"You could see the leg tape right away," Azarenka said. "But I wasn't really paying attention too much, because I had to play my game, and I had to keep her moving as much as I could."

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. Azarenka tossed away her racket, covered her face and hopped to the net. Her voice shook during the trophy ceremony.

"I'm sorry. I think I forget my English right now," she told the crowd. "It was such an honor for me to play Serena. She's the greatest player for me. I was so happy to be able to play her and win."

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 said she battled nerves Saturday, but they betrayed her only with an occasional double-fault. She was so poised serving in the final game that when she challenged a call and was advised the replay system had malfunctioned, she smiled and won the next point.

"She has really, really improved," Williams said. "I actually look forward to playing her again so I can play a little better, and obviously do better. She's going to be a really good player."