MELBOURNE, Australia -- Grand Slam tournaments are all about survival of the fittest. It's just that it's dicey business sometimes trying to guess who's truly fit.
Who would have thought a week ago that Jelena Jankovic could get the best of Serena Williams in Tuesday's quarterfinal? After all, it was the defending champion who came into the Australian Open pronounced leaner and just as mean. That observation proved to be as prescient as the barrage of criticism Williams received last year for showing up with a few extra curves.
This year, it's the outgoing 22-year-old Serbian who has played through aches and pains and browbeaten herself into form, ratcheting her level up with each match.
She came into the tournament gimpy. Jankovic strained a hamstring in the exhibition Hopman Cup to open the year and the rest of her body has paid the price for compensating ever since. She had to save three match points to avoid being eliminated in the first round by hard-hitting Austrian teenager Tamira Paszek, and said afterward the trajectories of the slice winners she struck must have been determined from above.
Jankovic picked apart Williams in her 6-3, 6-4 win, mostly by using her divine backhand to paint the corners and the lines at the right moments. It was an upset in terms of conventional wisdom, if not rankings, since Jankovic is seeded third, four spots above the eight-time Slam winner.
She clearly surprised even herself a little bit. Jankovic was so befuddled after Williams swatted a forehand wide on match point that she began walking to Williams' sideline chair.
"Defeating a defending champion, and a champion like Serena, is something that doesn't happen every day," said Jankovic, who advanced to her second career Slam semifinal.
"My game plan was just, I can do whatever, but just not give her the balls in front of her, especially when she serves. Obviously she's the best server out there, and she likes to get all the balls in front of her and really pound them. I just tried to move her and get the balls away from her, and it worked."
It worked especially well because Williams looked sluggish during stretches of the match. Jankovic's serve is not nearly on par with Williams', yet she managed to break the more powerful player seven times.
Williams had several hours to think about, if not cool off from, her defeat before she talked to reporters. She played doubles first with sister Venus, losing to a Chinese pair they could meet again at the Beijing Olympics this summer: Zi Yan and Jie Zheng.
The three-time Australian Open champion said she was not at her best physically but declined to be more specific.
"I'm not going to sit here and make excuses," she said in a subdued voice. "I lost because Jelena played better than me and I made too many errors. I think regardless, the match was on my racket, and I gave it away.
"I didn't move the way I traditionally want to move, and I wasn't feeling 100 percent. But as an athlete you know not every day you're going to feel 100 percent, and some days you have to win feeling 30 percent."
Both players received medical timeouts with Jankovic leading 3-2 in the second set. A trainer manipulated Jankovic's back and massaged her thigh as she lay with a towel draped over her head to shield her from the sun. Williams had someone attend to a blister on her big toe.
They walked back onto the battlefield and into a pivotal, lengthy game on Williams' serve that went to six deuces. Williams fought off break points with a fury, letting out a primal howl that echoed around Rod Laver Arena after one overhead winner, and wrapped it up when a Jankovic backhand sailed wide of the line.
But Williams couldn't hold serve in either of her next two chances and double faulted to set up match point.
Jankovic is now 3-2 against Williams, one of only two players in the WTA's top 10 (Russia's Anna Chakvetadze is the other, at 1-0) who's above .500. She is obviously proud of that, and of having defied people's expectations of her here. Some picked 30th-seeded Frenchwoman Virginie Razzano to beat her in the third round, and the papers were full of homeland hope for Perth native Casey Dellacqua before their fourth-round encounter.
"All these other girls who I played had the advantage over me for some reason," Jankovic said with a slight flip of her glossy black ponytail. "Even though I was better ranked on the paper, knowing that I'm injured they think that I cannot play. But I'm like a wounded animal, but I still keep going. The most important thing is that I fight on the court, and I always give my best and I never give up."
One of the biggest questions going forward for Jankovic is how much she should push through these spells. She played 97 matches last year and won 72, more than anyone else in the top 10. It's an ominous sign if she's already hurting in multiple spots with the season only a few weeks old.
"I cannot give you all the details, because if I would begin, I would never stop," she said.
When Jankovic felt a stabbing pain in her left quadriceps during that sixth game, before she called for a trainer, her first reaction was frustration.
"I thought, 'Oh my God, again, another one?'" she said. "I'm kind of sick of all these injuries. I want to be healthy and I want to play without any pains. But again, when I have pain, I focus more. When I don't have pains, I'm kind of like, 'OK, whatever.'"
Jankovic blew into the top echelon of the game last year like an exotic breeze bearing self-deprecating humor, infectious zest and the rich context of a new tennis nation rising. She's earthy, dramatic and tremendously likable even when she indulges in the occasional over-dramatization.
"They put me in an ice tub, a tub full of ice, and I freeze till death, actually, to kind of recover my muscles," she warbled in her low, operatic voice.
That treatment resulted in quite the eye-popping spectacle the other day. Jankovic wore her tennis dress into the ice tub and then ran across the grounds soaking wet to take a shower before meeting with the press. She laughed off the stares afterward; she considers everything in her life as potential material for performance art.
Jankovic's mental toughness has crystallized since her last Grand Slam semifinal, when she melted down against Justine Henin. Now she has to be vigilant about not beating herself up with that steel.
Bonnie D. Ford covers tennis and Olympic sports for ESPN.com. E-mail her at email@example.com.