MELBOURNE, Australia -- First glances, as it turned out, were utterly deceiving at the Australian Open.

Seventh-seeded Serena Williams showed up on Day 1 looking fit and eager, and at great ease, joking about dispensing relationship advice.
As for Jelena Jankovic of Serbia, she got through the first day by the slimmest of margins, needing to save three match points and seeming to be collecting new injuries by the minute.

Talk about Trading Places.

No. 3 Jankovic engineered the stunning switch with her usual moxie and her trademark backhand-down-the-line weapon, taking out the strangely muted defending champion, 6-3, 6-4, today in the Australian Open quarterfinals, creating shock waves around Melbourne Park.

How so?

Quite simply, Williams almost always does one of two things when it comes to the Australian Open. She either wins it, or doesn't play. The only time since 2001 neither of those two happened was when she lost to Daniela Hantuchova in 2003 in the third round.

And now to Jankovic.

"Oh my God . . . it was an unbelievable match," said Jankovic, who will play either No. 1 Justine Henin or No. 5 Maria Sharapova in the semifinals. "I'm still shaking.

"I'm so happy to be in semifinals for the first time in Australia. I came here with no expectations."

It sounded a lot like Williams when she showed up here last year, looking unfit and playing her way into shape during the fortnight, winning the title with grit, power and a formidable will.

Those qualities surfaced during the 1-hour 39-minute quarterfinal but only intermittently. Williams fought back from a 1-3 second-set deficit, and drew even after a marathon sixth game that went to six deuces.

She would win only one game after that.

Her power was marginalized by Jankovic's defensive abilities, but more damaging was Williams' lack of usual speed and often flat footwork. The serve was not able to bail her out either, as she double-faulted five times, the final one setting up Jankovic's match point.

Williams wasn't available for comment immediately afterward -- a doubles match with older sister Venus beckoned -- but her mother revealed in an interview in the hallway the reasons, in part, for some of her shortcomings against Jankovic.

"She's been having some problems," said Oracene Price, who is also her coach. "Whatever.

"Hmm. She's been having problems with her leg and her back and stuff and so all that's connected, they say. It's not really an excuse because I know she wouldn't want me to say that. But she just couldn't move like she usually moves.

"When she can't move . . . can't get to the ball."

Curiously, that had been the conventional wisdom about Jankovic, who needed treatment on the court before the sixth game of the second set for an injured left thigh and said the pain felt like "a knife went in my leg."

She possesses a twofold flair for drama on the court and the ability to deliver a great quote in the interview room, joking about needing a new leg after the tournament.

"I think I need to change my oil and my wheels," Jankovic said. "They're a little bit old. I think I have who knows how many thousands of miles to run more. So I think I should change at least one, so we'll see. This one that's taped would be good. It would be a good idea. Don't you think so?"

But the more-telling comment came earlier, perhaps a warning to the rest of the field. "I am like a wounded animal," Jankovic said.