Putting questions about her recent hip injury at rest, Capriati swept to an easy 6-4, 6-1 victory over Silvia Talaja of Croatia, needing just 62 minutes to decide the issue.
But, Hewitt became the first ever top seed at the Australian Open to lose in the first round when he fell to Alberto Martin, 1-6 6-1 6-4 7-6 (7-4).
Hewitt, who battled chicken pox earlier this month, won the first set in 31 minutes but appeared to tire as the match progressed. He was treated for foot blisters at 4-3 of the fourth set and had both groins massaged two games later.
"I'm not Superman," the 20-year-old as Australian said. "I was struggling out there and at the end of the first set I started to feel tired. I tried to hit a lot of winners, but it's a lot slower out there and the balls are heavier this year. God knows why."
It was an injury timeout called by Martin that proved controversial. The Spaniard had ATP trainer Bill Norris come to the court while leading, 5-4, in the tiebreaker. Hewitt felt it was a matter of gamesmanship.
"You can read into it what you like," he said. "You never know if I would have got out of the situation, but it would have made it a lot easier if we had played fair. I had asked for the trainer before, but I told the umpire I would wait for the change of ends just because it's not the right thing to do at 30-30.
"I won't make an official complaint. Enough people have seen it and if nobody does anything there's not much point me going and arguing."
After the break in action, Hewitt hit a backhand long and a forehand into the net.
"It was a dogfight for me, but I'm not as disappointed as in other matches because I knew I wasn't 100 percent," he said. "I did the best I could. I hadn't played a serious match for a week
and a half or two weeks and if this had been a regular tour event I wouldn't have been playing.''
Hewitt was the first Australian since Ken Rosewall in 1976 to earn the No. 1 seed here. He earned the world's top ranking last year after capturing six titles, including his first career
Grand Slam at the U.S. Open and the Tennis Masters Cup in Sydney.
Hewitt, playing in Rod Laver Arena for the first time since Australia lost the Davis Cup final to France in December, was bidding become the first Australian since Mark Edmonton in 1976 to capture the men's crown here.
Martin, ranked 39th, has advanced to the second round in Melbourne for the second straight year, but has yet to get past the third round of a Grand Slam in 14 attempts.
Capriati returned to the scene of her first Grand Slam crown.
She upset three of the top four players in the world to become the lowest seed (12th) women to win a major title in the Open
Era. The 25-year-old American went on to claim a second Grand Slam at the French Open in June and briefly rose to the No. 1 ranking in October.
"I felt more of the butterflies earlier in the week; when I made the trip over here I was feeling it," she said. "But since I've been here, being around the grounds and practicing, I felt OK I
felt, more than anything, excited, and couldn't wait to get out there."
Capriati's preparations for this event were stalled last week when she suffered a hip injury in last week's second-round loss Sydney.
"It wasn't my day that day, and I was really looking forward to getting here and starting here, and maybe I was looking too far ahead of myself," she said. "But that's exactly why it's called
a warm-up tournament."
Capriati did call for the trainer Tuesday, but it was only to adjust the tape around her upper right leg.
"It's been a week since I hurt it," she said of her injury. "I think I moved pretty well out there; I felt comfortable. I've been able to train full-out over the last few days."
Health has been a major factor at the Australian Open so far. On Monday, third-seeded two-time defending champion Andre Agassi
In addition, second seed Gustavo Kuerten of Brazil re-aggravated a hip injury during a five-set loss to France's Julien Boutter.
This is the first Grand Slam since the 1990 French Open that two top seeds have lost in the first round.
On Tuesday, two-time champion Pete Sampras, hoping to break out his worst title drought in 12 years, easily posted a 6-3, 6-3, 6-4 victory over Jarkko Nieminen -- a Finn playing in his first
"I was pretty pleased," Sampras said. "I set the tone early on. He came out a little nervous and I took advantage of that."
The eighth-seeded American has not won a tournament since 2000 Wimbledon, when he set the all-time record for most Grand Slam singles titles in a career with his 13th. Last season was the
first year he went without a tournament victory since 1989.
Federer started the season by going 1-2 for Switzerland in the Hopman Cup but rebounded with a tournament victory at Sydney.
No. 13 Andy Roddick of the United States makes his Australian Open debut against Mariano Zabaleta of Argentina. He is no stranger to Melbourne, though, having won the junior boys' title two years ago.
The 19-year-old American played his first full year on the tour in 2001 and had a sensational season. He won three titles and reached the quarterfinals of the U.S. Open to climb 144 places
in the rankings to No. 14.
Roddick made his season debut last week at Sydney and reached the semifinals.
Also, seventh seed Tommy Haas of Germany routed Russian Andrei Stoliarov, 6-1, 6-3, 6-1; No. 9 Marat Safin of Russia topped Frenchman Anthony Dupuis, 7-5, 6-4, 6-2; 15th seed and last year's finalist Arnaud Clement of France defeated Flavio Saretta of Brazil, 6-4, 7-6 (7-5), 5-4.
On the women's side, sixth seed Justine Henin of Belgium slowed Anna Kournikova's comeback from last year's foot injury with a 6-2, 7-5 victory over the unseeded Russian.
Henin was not intimidated by the usual uproar caused by Kournikova, who caused a sensation when she took the court wearing a turquoise outfit of hot-paints and sleeveless top with a white belt and sun visor.
"I played against a personality and the crowd love that," said Henin, who recorded her third win as many meetings with Kournikova. "It is always difficult when you are in front of her to give 100 percent because you have to stay focused just on the match."
The 19-year-old Belgian is coming off the best season of her career when reached her first final in a major last year, losing the championship match to Venus Williams at Wimbledon. Henin won three tournaments, and teamed with Kim Clijsters to lead their country to victory at the Fed Cup last November.
Kournikova reached the quarterfinals here last season and was ranked as high as No. 8 eight months ago, but was unseeded this year after missing much of 2001 with a left foot stress facture.
"I have got to be positive," she said. "I have plenty of time and I'm getting better with every match. I hope to get back to where I was before the injury."
Clijsters, the fifth seed, crushed Australian wild card Christina Wheeler, 6-2, 6-1. She also won three titles last year and appeared in her first Grand Slam final at the French Open.
Seventh seed and 1999 runner-up Amelie Mauresmo of France thrashed Janet Lee of Taipei, 6-1, 6-0, in just 49 minutes; No. 10 Meghann Shaughnessy outlasted fellow American Alexandra
Stevenson, 6-7 (5-7), 6-2, 7-5; and No. 12 Elena Dementieva of Russia beat countrywoman Alina Jidkova, 6-3, 6-2; No. 16 Iroda Tulyaganova of Uzbekistan cruised past Argentina's Maria Emilia
Salerni, 6-3, 6-4.
2014: The Year in Music [PHOTOS]