Serena Williams fell short in extending the tournament winning streak that she and sister Venus put together as she was forced to retire in the third set of today's final against defending champion Martina Hingis at the $1.08 million du Maurier Open.

The highly anticipated final between two of the top teenagers in women's tennis saw Williams storm through the first set, 6-0. But Hingis bounced back to take the second set, 6-3, and raced to a 3-0 lead in the final set before Williams informed the chair umpire she was unable to continue.

The injury was diagnosed as an inflamed left foot.

"It was two different matches out there today," Hingis said. "I was worried I might lose, 6-0, 6-0, but I just kept at it. I could see she wasn't moving well in the third set, but I didn't want to give her an opening."

Hingis captured her 31st career singles title and fifth of the season -- first on hard courts -- and a first prize of $166,000. She became the fourth female since 1980 to successfuly defend her title here, joining Martina Navratilova, Chris Evert and Monica Seles.

Hingis, 19, improved her season record to 53-8, including 30-5 on hard courts, and stopped a three-match losing streak to Serena Williams. She avenged a three-set loss to Serena Williams in the semifinals of last week's estyle.com Classic in Los Angeles and leveled the all-time series at four matches apiece.

The reigning U.S. Open champion, Serena Williams saw her nine-match winning streak come to an end, as well as the four-tournament streak of the Williams sisters. Venus Williams captured three straight events before Serena won last week's tournament.

The Williams sisters had combined to win 29 straight matches before today's loss, dating to when Venus beat Serena in the semifinals at Wimbledon.

Serena Williams, 18, was seeking her eighth career WTA Tour title and third this season.

This is the last year the event was known as the du Maurier Open because of recently passed laws barring tobacco companies from sponsoring sports events. Next year, it will be called the Roger's AT&T Canada Cup.