Miami  - Teenaged talent Victoria Azarenka lifted her third title of 2009 as she stunned world number 1 Serena Williams 6-3, 6-1 on Saturday to win the Miami Masters.

The Arizona-based player from Belarus denied Williams a record- setting sixth trophy in just 72 minutes, breaking five times at the event where the American and her sister Venus have won eight of the last 11 women's titles.

Azarenka played strategically against top seed Williams who came to court with her left thigh heavily strapped and was limited in her range of shot.

Azarenka had a nervous finish, striking two double-faults in the concluding game as she tried to serve it out. The youngster eventually came through on her third match point after saving a pair of break points as Williams returned long for her 34th unforced error.

"I was so nervous up 5-1 trying to close it out," admitted the winner, who also claimed titles at Brisbane and Memphis in 2009. "I couldn't believe that I had a match point.

"I didn't know what would happen, But then I double-faulted (on her second) and didn't know what do to next. I'm just so happy to have won."

The challenger, who stood outside the Top 500 five years ago at age 14, will be established solidly inside the Top 10 at number 8 after her upset. The win over Williams follows a victory against world number 2 Dinara Safina at her last event in Indian Wells.

"It was so tough, I'm just glad to have made it this far," said Williams, who refused to speak of her injury worry. "I give Victoria all the credit."

Added Azarenka: "It's such an honour to play Serena," she said of the 10-time Grand Slam winner who had beaten her in both of their previous matches, the last when the teenager was unable to carry on after feeling ill in Australian Open hothouse conditions in January.

"Serena is the greatest for me," said Azarenka. "I'm so happy to be able to beat her.

"I've improved almost everything in my game, and I've started to believe in myself a bit more. I now know that I can win tournaments and play well."

Williams, who will stay atop the WTA rankings for another week despite the loss, showed her lack of form from the start, losing serve in the third game but getting it straight back.

But the effort could not last for the limping player who was unable to put her full weight onto her left leg. Azarenka broke Williams twice more to lift the opening set her her fourth chance as the American plowed a weak backhand into the net.

Azarenka stamped her authority on the second set as the fading Williams double-faulted away the fourth game to trail 1-3.

From then on, it was a matter of minutes before Azarenka claimed the win, her 23rd of the season against just two losses.

The Belarus player becomes only the sixth teenaged winner in the event's history along with Steffi Graf, Monica Seles, Gabriela Sabatini, Martina Hingis and Venus Williams. (dpa)