Defending champion Serena Williams slumped out of the Australian Open in a 6-3, 6-4 quarterfinal loss to third-ranked Jelena Jankovic.
Williams, who was unseeded and ranked No. 81 when she won here last year for her eighth Grand Slam title, struggled with her serve on Tuesday and made 36 unforced errors trying to combat Jankovic's go-for-broke game.
Williams had not dropped a set in her four previous matches but looked sluggish after winning the first two games. Her usually powerful serve was broken three times in the first set and four times in the second.
Jankovic served for the match at 5-3, only to be broken herself. Williams led 40-15 in the next game only to fall apart again, double-faulting to set up match point, then sending a forehand wide. "It was an unbelievable match, I am still shaking," said Jankovic, reaching the semifinals for the first time at Melbourne Park and only the third time at a major.
"I came here with no expectations it's amazing to beat the defending champion and in general a champion like Serena, it doesn't happen every day."
Williams immediately went to join her sister, Venus, to prepare for a doubles quarterfinal.
Second-ranked Rafael Nadal was impressive in a 7-5, 6-3, 6-1 win over No. 24 Jarkko Nieminen of Finland, making the semifinals for the first time in four trips to the Australian Open. He set up match point with a stunning forehand down the line and closed with an overhead smash as Nieminen charged the net. Three-time French Open champion Nadal, the only player to beat Roger Federer in the last 10 Grand Slam tournaments, next faces the winner of Tuesday's later quarterfinal between No. 14 Mikhail Youzhny faces Jo-Wilfried Tsonga of France.
"I'm very happy to be in the semifinals in this tournament. It's a very important tournament for me at the start of the season," Nadal said. "I've had a very good tournament so far." Jankovic had to fend off three match points in the third set of her first-round match, which included 15 service breaks, before edging Tamira Paszek, 2-6, 6-2, 12-10.
She followed that with straight-sets wins over Edina Gallovits and Casey Dellacqua and was taken to three by No. 30 Virginie Razzano.
Jankovic lost to Williams in the fourth round here last year between runs to the semifinals at the 2006 U.S. Open and 2007 French Open her best efforts in Grand Slam tournaments to date. "Now, getting revenge it feels so good," said the 22-year-old Jankovic, who is now 3-2 in her career against Serena Williams. "I've beaten the Williams sisters a couple times. But here it is very special."
After taking the first two games, Williams became increasingly sluggish and was often caught flatfooted, left to watch as Jankovic's shots landed for winners or to whack unforced errors awkwardly into the net.
Her shoulders frequently drooped as the points piled up against her.
The fans shared her disbelief, with one shouting: "Wake up Serena!" By the time sister Venus showed up, Williams had lost the first set squandering five break points in two games and netting an easy forehand volley on set point.
After Jankovic broke her for a 3-1 lead in the second on a stinging backhand, Williams angrily spiked her racket, earning a warning from the umpire for racket abuse.
That seemed to kick-start her for a while, as Williams broke in the next game to get back on serve.
Both women received medical treatment at the changeover, Jankovic for a persistent thigh ailment and Williams for a blister on her right big toe.
Top-ranked Justine Henin was to play No. 5 Maria Sharapova, the losing finalist last year, on Tuesday night.