SACRAMENTO, CALIF. ? Marion Jones, her vulnerability seeming to grow with each event, finished a shocking seventh but managed to advance to the final of the long jump at the U.S. Olympic trials.

Jones, by far the best U.S. long jumper in a weak field, was among the 12 qualifiers who advanced to Thursday’s final. But she failed by a quarter-inch to reach the automatic qualifying mark and got worse with each of her three jumps Monday night.

Jones, who won an unprecedented five medals at the 2000 Sydney Games, failed Saturday night to make the U.S. squad in the 100 meters — an event in which she is the defending Olympic champion.

Her qualification virtually was taken for granted in the long jump, in which she won a bronze medal in Sydney and in which only one other American this year has met the Olympic qualifying standard.

Now, though she probably will make the team, it suddenly is not certain.

Under qualifying rules, Jones provisionally can make the Olympic team even if she fails to place among the top three Thursday night. That’s because only she and Grace Upshaw have Olympic qualifying marks this season.

So, even if Jones finishes last among the 12 competitors in Thursday’s final, she’ll still be named to the squad if no other jumper has reached the Olympic qualifying mark. But the top two finishers Thursday still could bump her from the team if they get a qualifying mark of 21 feet, 113/4 inches by Aug. 9.

Jones never smiled during her three jumps. She took off well before the foul line on each of her attempts, but never seemed to soar. As in the 100 two days earlier, she seemed to lack an extra gear.

Jones’ best jump came on her opening attempt.

Marion Jones lands after her first jump in the women's long-jump qualifying round at the U.S. Olympic track and field trials. Jones on Monday advanced to Thursday's finals in the event in Sacramento, Calif.

The first competitor in the first qualifying round, Jones quickly took off her long-sleeve white shirt and threw her black sweat pants to the side. She stepped up to the end of the long jump runway.

She took a deep breath, her cheeks puffing out as she inhaled. Then she quickly exhaled, lifted her head and started speeding toward the sandy pit. She landed 20 feet, 113/4 inches from the line — just a quarter-inch short of the qualifying mark.

Her next two jumps were shorter — 20-93/4 and 20-81/2.

Meanwhile, the last of the BALCO Four — those athletes charged with steroid use by USADA — was eliminated at the Olympic trials.

Alvin Harrison, one of four athletes who faces a lifetime ban if found guilty of using steroids obtained from the Bay Area Laboratory Co-Operative, failed to qualify for the final of the men’s 400 meters.

He joined fellow accused dopers Tim Montgomery and Chryste Gaines in failing to qualify for the U.S. team for the Athens Games. The fourth accused doper, Michelle Collins, pulled out of the women’s 400 claiming a hamstring injury.

Harrison finished seventh in his semifinal, fading after being among the leaders until the final straightaway. Then he threatened to sue USA Track & Field, claiming “bias and discrimination.”

By failing to qualify, the four accused dopers saved the U.S. Olympic Committee the embarrassment of having to remove them from the team if arbitrators rule they are guilty.

Also failing to qualify for the final was world champion Jerome Young, who faces the loss of his relay gold medal from the 2000 Olympics because of steroid use.

In other action Monday night, Jearl Miles-Clark earned a trip to her fifth Olympics by winning the women’s 800 meters.

Jonathan Johnson won the men’s 800 in 1:44.77 to earn an Olympic spot along with Khadevis Robinson and Derrick Peterson. James Parker won the men’s hammer throw. Aretha Hill won the women’s discus. Shayne Culpepper won the women’s 5,000. Tisha Waller won the women’s high jump, but failed in three attempts to break the U.S. record.