Del Potro is first big name to fall

After a quiet start, the Australian Open roused itself Saturday and shook things up a little.

The record crowd packing the grounds saw No. 6 seed Juan Martin del Potro go down a set, then two. After coming back to force a fifth set, del Potro finally was toppled by Jeremy Chardy in the biggest upset of the tournament to date.

Other big names got a scare. Defending champ Victoria Azarenka was taken to a third set. Serena Williams lost three games in a row (which qualifies as a big event).

Even Andy Murray found himself down a break in the second set, but he came out ahead in more ways than one -- he handled Ricardas Berankis 6-3, 6-4, 7-5 and now no longer has to worry about a potentially tricky quarterfinal encounter against del Potro.

After starting the tournament looking like a threat to the top three, del Potro, a former U.S. Open champ, looked subdued in his afternoon match. Chardy, who said afterward he felt he had nothing to lose and could swing freely, took the first two sets in a flurry of forehand winners.

But the unseeded Frenchman couldn't quite close it out in the third, playing tamely in the tiebreak to let del Potro back in the match. Del Potro seized the opportunity and also grabbed the fourth set, but Chardy collected himself to break for 5-3 in the fifth and remained calm when serving out the match.

"From the first point to the last point, I played exactly the same," Chardy said, adding that his strategy was to use his slice backhand and go for his forehand when given the chance. "It's a big win for me."

One of del Potro's few explosive movements came when he jumped the courtside barrier after running for a ball, but he never consistently found the commanding groundstrokes that had many observers tipping his chances in the first two rounds.

He consulted with the trainer at one stage in the match and was given some tablets in response.

"I'm feeling OK," said del Potro, who is usually reluctant to talk about physical problems after matches. "He deserved to win the match in the end."

Hampton impresses Azarenka

The day began with Azarenka in trouble against young American Jamie Hampton. Azarenka pulled out the match 6-4, 4-6, 6-2, but it was Hampton's big hitting that impressed a lot of people -- except herself.

"I put in a lot of hard work during the offseason, so I was not surprised," the 23-year-old Alabaman said matter of factly, after hitting 41 winners to 17 for Azarenka.

Her opponent certainly was surprised.

"I think she surprised everybody a little bit today," Azarenka said. "I didn't really see her play before, but my coach watched and he said she didn't play like that other matches that he saw.

"But she definitely went for everything there was today. And I know the same feeling when you go and you have nothing to lose -- you're so loose, you're free and you feel like you can't miss it."

That might have been necessity rather than design, because the match began very differently. Azarenka quickly went up 5-1 in the first set, but Hampton dug in, narrowing the gap to 5-4 before losing the set and then going up 5-4 in the second.

However, by this time the American was battling a second opponent -- pain from the two herniated disks in her back, rippling into cramps in both legs. After receiving treatment, Hampton battled on gamely for a while, serving out the second set and going up an early break in the third.

Although barely able to move at times, she made up for it by swinging her forehand like a sledgehammer, and for a while, they were all finding their mark.

"She took a medical timeout, but she rips winners all over the place. And I was like, 'Can I have a back problem?'" Azarenka joked a little caustically afterward.

But faced with the prospect of losing her title and No. 1 ranking, Azarenka's intensity -- and grunting -- reached a new pitch in the third set. Barely containing an explosion after going down 2-1, she collected herself and navigated past the fading Hampton without losing another game.

Hampton said her back injury, which was discovered at the French Open last year, began bothering her midway through the second set.

"It's something I deal with day to day, and, yeah, it was hurting," she said. "Normally when my back starts hurting, I start cramping."

A hiccup for Serena

Another person not surprised by Hampton was Serena Williams, who practiced with her younger compatriot at the U.S. Fed Cup tie against Ukraine in April last year.

"I loved hitting with her. I thought she was just an open gem. It looks like she finally cracked open and she's showing her true colors," Williams said. "But I wasn't surprised, because I only wanted to hit with her because she was hitting so well."

Williams was, however, a little surprised by her Saturday opponent, Ayumi Morita, who went ahead 3-0 in the second set to briefly hold up Williams' 6-1, 6-3 progress to the fourth round.

"She played at a level higher than I expected so it took me off guard," Williams said.

But more than anything, the third seed and title favorite was relieved to get through her match without any physical mishaps. She rolled her ankle in her opener Tuesday and smacked herself in the lip Thursday.

"I don't know what's going to happen on Saturday," she had joked heading into the match.