SYDNEY, Australia (AP) _ Marion Jones could have coasted. Instead, she put on a show of speed on her way to the semifinals of the women's 100.

Jones underlined her quest for five gold medals at the Sydney Games by running the second-fastest 100 of the year, winning her second-round heat Friday in 10.83 seconds. The only faster time this year was 10.78, run by Jones in London on Aug. 5 and Berlin on Sept. 1.

"Perhaps if our semis tomorrow were a bit earlier, I would have laid back a little bit," she said. "We have all day tomorrow to kind of rest and relax. That's why I decided tonight, `Aw, put one out there."'

Maurice Greene also had two early-round wins to reach the men's 100 semifinals Saturday. His time of 10.10 seconds in the second round was the second fastest of the day _ only Obadele Thompson was quicker at 10.04.

Michael Johnson and Cathy Freeman had first-round wins in the 400 as track and field events began Friday.

Jones and Greene, both of whom were merely spectators at the 1996 Atlanta Games, showed why they're clear favorites in Sydney.

Jones qualified for U.S. relay teams for the 1992 Barcelona Games, but decided not to go. A broken bone in her foot ended her hopes of competing at Atlanta four years ago.

"I feel great, I feel great. You know, it's been a long time. I was just waiting and watching. But it's here now, so no more excuses," said Jones, who took it easy in her first-round heat. "I'm having a ball. I'm 24 years old, I'm in Sydney, I'm running great."

Joining Jones in the semifinals of the women's 100 was U.S. teammate Chryste Gaines. But Torri Edwards, a late replacement for the injured Inger Miller, was fifth in her second-round heat and failed to advance.

Also reaching the semifinals was Merlene Ottey, a seven-time Olympic medalist who substituted at the last minute for teammate Peta-Gaye Dowdie _ leading to protests by some Jamaican team members.

After Greene moved into the semifinals, he waited near the finish line for Sydney housemate and training partner Ato Boldon, who won his heat in 10.11 seconds. Also advancing to the semifinals were Americans Jon Drummond and Curtis Johnson.

But defending champion Donovan Bailey, who spent the past few days battling the flu, ran out of steam in his second-round heat and was eliminated.

Greene, who holds the world record of 9.79 seconds, failed to qualify for the 1996 Olympics and drove 18 hours from his home in Kansas City to Atlanta to see the games. During the 100 final, he sat in the stands and cried uncontrollably.

"I'm not putting too much pressure on myself, even though there's a lot of pressure out here," Greene said Friday.

Arsi Harju of Finland won gold in the men's shot put with a toss of 69 feet, 10¼ inches. The other two medals were taken by Americans _ Adam Nelson was second with a throw of 69-7 and 1996 silver medalist John Godina won bronze with 69-63/4.

Godina was a late replacement for U.S. teammate C.J. Hunter, the reigning world champion. Hunter dropped out after arthroscopic knee surgery.

Charles Austin, the defending champion in the men's high jump, failed to advance out of the qualifying round. But 1992 Olympic champ Javier Sotomayor, who returned to competition in mid-August after track and field officials cut in half a two-year ban for cocaine use, reached the high jump final.

Freeman is seeking to become the first Aborigine to win an individual Olympic gold medal. She received thunderous applause from her fellow Australians in the 110,000-seat Olympic Stadium.

Freeman won her heat in 51.63 seconds. She has not lost a 400-meter race in three years and is even more of a favorite at the Sydney Games now that two-time defending champion Marie-Jose Perec has fled the Olympics.

Also advancing to the second round of the women's 400 were Americans LaTasha Colander-Richardson and Monique Hennagan.

There was an empty spot in lane three of the fifth heat of the 400. That spot would have been taken by Perec, who left Sydney a day earlier after claiming she was threatened by an unidentified man.

In the first-round heat of the men's 400, Johnson glanced to his left several times down the closing stretch to see if anyone was close behind. He didn't need to bother. He cruised to an easy victory in 45.25 seconds.

Johnson is an overwhelming favorite to become the first man to win the event in consecutive Olympics.

Joining Johnson in Saturday's second round were U.S. teammates Alvin Harrison and Antonio Pettigrew, who also won their heats. Harrison, wearing a full body suit and long sleeves on a hot, sunny day, had the fastest qualifying time of 44.96.

The Clark clan had a good day in the women's 800 meters. Joetta Clark-Diggs, her kid sister, Hazel Clark, and their sister-in-law, Jearl Miles-Clark, all easily advanced to the semifinals.

The first track medal of the games was mired in controversy. Mexico's Bernardo Segura crossed the finish line first in the 20-kilometer walk, but later was disqualified for breaking contact with the ground.

That gave the gold medal to Poland's Robert Korzeniowski, with Noe Hernandez of Mexico second and Vladimir Andreyev of Russia third.

(Copyright 2000 by The Associated Press. All Rights Reserved.)