Fifteen-year-old Sesil Karatantcheva was almost too scared to win. In the future, her opponents are more likely to be terrified by the speedster.

The Bulgarian's first name rhymes with special and her last name is so long she may come to be known as Special K.

She beat four-time Grand Slam winner Venus Williams [Images] in the third round and advanced to the quarter-finals of the French Open on Sunday after defeating Emmanuelle Gagliardi 7-5, 6-3.

The straight-sets score didn't reveal the anxiety she felt.

"I was basically scared to win," she said. "Just the thought of me being in the quarter-finals in Paris was just too scary for me. I guess the pressure really is getting to me. I hope for the quarters I'll be more relaxed."

Reaching the final eight of a Grand Slam hit her so hard she fell to the court, lay on her back and clasped both hands over her face as the weight of her achievement sank in.

Gagliardi wasn't surprised and predicts future stardom for Karatantcheva, the junior champion at Roland Garros last year.

"There are a number of very young players emerging and she's one of the best ... very, very promising," Gagliardi said.

"She hits very strongly, it's so difficult to beat her for speed," she added. "I tried as much as possible but I couldn't manage. You have to run so much to put her in a difficult position."

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Karatantcheva now faces No. 16 Elena Likhovtseva of Russia [Images], who beat last year's runner-up and No. 4 seed Elena Dementieva 7-6 (3), 5-7, 7-5.

Karatantcheva took Williams by surprise -- she'd never even heard of her before their match.

Others, like Wimbledon [Images] champion Maria Sharapova [Images], did their homework before facing her. Sharapova recently acknowledged she had been very wary of facing Karatantcheva in the first round of the Australian Open [Images]. Sharapova won that match 6-3, 6-1.

Karatantcheva has reached her second quarter-final of the season, having lost to Patty Schnyder of Switzerland [Images] on a hardcourt at Gold Coast, before the Australian Open.

"I do believe I can play a lot better," Karatantcheva said. "I don't know where that is going to take me but wherever it is, I'm already happy enough."

Karatantcheva speaks English fluently, learning the language from listening to Spice Girls [Images] songs, then practicing it while training at the Nick Bollettieri Tennis Academy in Florida [Images]. She was best known before this tournament for a comment she made last year at age 14. Before a match against Sharapova, Karatantcheva pledged to "kick her butt" because of a perceived slight during training.

Karatantcheva later characterized the remark as youthful indiscretion.

These days, Special K is making a name for herself and making it hard for friends and family to reach her.

"I'm not even answering my phone," she said. "I had 20 missed calls yesterday. A lot of people are very happy for me, a lot of kids, a lot of adults."

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