Caroline Wozniacki -- a knockout in training

Let's see. No. 1 women's seed Caroline Wozniacki is a pretty blonde from Denmark who also is proud of her Polish ancestry and is a bright, charming person capable of speaking several languages quite well.

All impressive qualities indeed. But there was something else about her, some indefinable characteristic that made her even more attractive. I couldn't quite put my finger on it until her news conference tonight. That's when Wozniacki revealed that her training routine includes boxing, and she's a fan of a couple of terrific European fighters.

Be still the heart of a long-time boxing writer. I married the last woman who told me she liked boxing.

Following her 6-2, 7-5 quarterfinal victory over Dominika Cibulkova tonight in the U.S. Open, Wozniacki was questioned about why she incorporates boxing into her training. "Boxing is a different way to work, and it's fun," she said. "I have a great coach who knows how to get me in shape for tennis as well. I love the training. It's great to have a coach who pushes you to the limit."

Naturally, Wozniacki said she's a supporter of Denmark's Mikkel Kessler, the WBC super middleweight champion, whom she describes as a friend. But she added that she also was a big fan of Joe Calzaghe, the Pride of Wales, who held all the major super middleweight belts before retiring with a 46-0 record, including 32 knockouts. "When he was fighting," Wozniacki said, "he was amazing."

Spoken like a true boxing fan. Asked by the great S.L. Price of Sports Illustrated if she ever knocked anybody down, Wozniacki smiled and said, "No, I'm a good girl."

But my Newsday colleague Jeff Williams tells me that, as a junior in 2006, Wozniacki was defaulted for verbal abuse of a match official. That temper was on display tonight when she berated the chair umpire for allowing Cibulkova to replay a point following a delayed call on a ball she hit wide. "I'm really competitive," the pugnacious Wozniacki explained. "I don't like losing."

Wozniacki might be tough as nails when it comes to the way she trains and competes, but as the ever-inquisitive Price uncovered, her nails are exquisite. Price (who, quite seriously, is my nominee for best sports writer in America) wondered why Wozniacki, who sported dark-colored nails for the first match, had changed to a bright, sparkly yellow.

She explained that she needed a color that matched her outfit -- green dress, yellow trim -- and the color of the tennis balls and just the general décor at the Open. "I do it myself," she said of the nail job.

She plays great tennis, knows boxing and does her own nails? That's a knockout combination any way you cut it.