MELBOURNE, AUSTRALIA - Third-seeded Jelena Jankovic beat defending champion Serena Williams and advanced to the Australian Open tennis semifinals for the first time on Tuesday.

After twice being taken to three sets at Melbourne Park this year, Jankovic outmaneuvered the eight-time Grand Slam champion at Rod Laver Arena to complete a 6-3, 6-4 victory.

"I came here with no expectations," Serbia's Jankovic said in a courtside interview. "It's amazing to beat the defending champion and a champion like Serena. It doesn't happen every day."

On the men's side, second-seeded Rafael Nadal reached the final four in Melbourne for the first time. Nadal opened men's quarterfinal action with a 7-5, 6-3, 6-1 rout of 24th-seeded Jarkko Nieminen, maintaining his record of not dropping a set at this year's tournament.

Seventh-seeded Williams, who clinched the title last year when ranked 81st, lost her service seven times and struggled with her movement, opting not to chase down several balls.

The 26-year-old American berated herself with a call of "move your feet" and received a warning from the chair umpire for racquet abuse after losing her service for the fifth time to trail 3-1 in the second set.

Jankovic, 22, broke again four games later for a 5-3 lead, then lost her service before finally dispatching Williams with another service break.

She reached the third Grand Slam semifinal of her career and will face the winner of the match between top-seeded Justine Henin and No. 5 Maria Sharapova.

Henin and Sharapova play for the ninth time in their first meeting since the Belgian won a 3-hour, 24-minute tussle in the Tour Championships final two months ago.

According to Henin, that match signaled the Russian's return to the sort of form that lifted her to Wimbledon and U.S. Open titles.

"It showed she was back at her best," Henin said after beating Taiwan's Su-Wei Hsieh in the fourth round. "She's a real fighter and never gives up. I'll have to be at 100 percent the whole time."

Henin takes a 32-match winning streak into the meeting at Rod Laver Arena, where she won the title in 2004. After skipping last year's Australian Open, she won 10 of 14 events to complete a career-best season and carried her winning form into 2008 by claiming the Sydney International title.