Just days after being ranked No. 6 on Mr. Blackwell's annual worst-dressed list, Serena Williams (search) unveiled her new line of lime green-and-white Nike tennis apparel.

She co-designed a three-in-one dress and knee-high boots.

Williams, No. 7 in the world tennis rankings, modeled the outfit Thursday, stepping out of the dress to reveal what she'll be wearing at the Australian Open (search) next week: a top and shorts that are just "ideal" for practice.

Unconventional? "You bet!" she said.

Like the black knee-high warm-up boots that made headlines at the U.S. Open (search) in August, the new boots can be unzipped and removed between the warm-up and a match.

"My legs take a little longer to warm up than the next opponent, so it's perfect for me, they'll keep me warm and then I'll be able to blast off," she said.