INDIANAPOLIS, AUG. 13 -- Jackie Joyner-Kersee and her husband/coach Bob Kersee argued for weeks over whether she should risk injury before the upcoming world championships by competing here in these 10th Pan American Games. Fortunately for both, and a near-capacity crowd of 10,504 at the Indiana University Track Stadium, Jackie's stubbornness won out.

Joyner-Kersee shattered her U.S. long jump record twice tonight and, on her sixth and final jump, tied the world record of 24 feet 5 1/2 inches (7.45 meters) shared with East Germany's Heike Drechsler. She became the first American woman to hold at least part of a world record in a field event in 10 years.

Bob Kersee was ready for all the I-told-you-so's his wife could muster. He fell to the ground and wept openly after an eight-minute wait in which a steel tape measure was brought out to confirm the initial measurement. "I'll never doubt her again," he said.

Silver medalist and teammate Jennifer Inniss stood with Joyner-Kersee during the measuring delay, trying to convince her she had just finished an extraordinary jump. "I said, 'No, it wasn't that far out there.' But we waited so long {for confirmation} that I started to think that we must be waiting for something," Joyner-Kersee said.

Her performance tonight was easily the highlight of the Games, a bit of high, prime-time drama this competition needed. It far overshadowed a fine afternoon by the U.S. swimmers, the first full evening of boxing and gymnastics, and a one-two finish by Americans in the decathlon.

Joyner-Kersee said she didn't have any indication this would be a record-setting evening. "I felt my legs were sluggish coming into the event," she said. "After my first jump {23-4 3/4}, I figured I'd either mess it up or put it all together."

She fouled on her second jump, then came back with a 23-9 1/2 to break her U.S. record of 23-9. Her fourth jump resulted in 23-8 and a fall in the pit; the fifth was 23-5 1/2.

"My second jump was the best of all, considering the speed, my last four strides and my knees being up," she said. "It's really unfortunate that one was a foul. The last jump, I prayed for strength. I was holding my legs up for as long as I could."

Kersee recommended his wife not compete here: "She had tendinitis in her knees from jumping indoors. . . . She had to pull out of the heptathlon {in which she holds the world record} four years ago after she had injured her hamstring in the long jump."

But Joyner-Kersee said she "needed some more work" and they decided she would long jump only. Said Kersee: "She really wanted to come here and compete for the American people after winning the Sullivan Award {as the U.S. top amateur athlete}."

There were other events tonight. Mike Gonzales, a recent graduate of Southern Cal, took the gold medal in the decathlon, with a score of 7,649, edging Brigham Young's Keith Robinson, who settled for the silver when a groin injury hurt him in the crucial pole vault.

In the 400 meters, Raymond Pierre, a Washington, D.C., native and a junior at Baylor University, took the gold medal by scoring an upset over Cuba's Roberto Hernandez. Pierre's time of 44.60 edged Jamaica's Bertland Cameron (44.72) and Hernandez (45.13).

American Coleen Sommer, attempting a comeback after an auto accident and long layoff in 1986, earned the gold medal in the women's high jump, beating Cuba's Silva Costa. Sommer's jump of 6-5 1/4 is a Pan Am record.

Another American, Marty Cooksey, won the women's 10,000 meter run in 33 minutes.

Boxing:

Competition opened at the Convention Center with two U.S. medal contenders winning preliminary bouts. At 125 pounds, world champion featherweight Kelcie Banks, 22, dispatched Marcos Cristofalo of Argentina with a 5-0 decision, and 178-pound light heavyweight Andrew Maynard, a 22-year-old U.S. Army product from Cheverly, Md., defeated Oscar Gonzalez of Argentina by a knockout with eight seconds left in the first round.

"The way I look at it, this is my house," Maynard said of the Convention Center, where a crowd of 3,350 roared at his knockout.

Maynard's and Banks' victories set up the first U.S.-Cuba bouts. Banks meets Arnaldo Mesa in the quarterfinals Sunday. Mesa advanced tonight with a 5-0 decision over Venezuela's Omar Catari, the bronze medalist at the Los Angeles Olympics. "I dedicated tonight's fight to my home and to Castro, who is 61 today," Mesa said of his victory.

Maynard has a semifinal meeting Wednesday with Cuban world champion Pablo Romero, who defeated Canada's Brent Kosolofski with a 5-0 decision in a long-distance punchout.

Maynard dropped Gonzalez to one knee with 36 seconds left in the round when he landed a left-right combination that drew an eight count. Maynard waded in again, and a flailing left dropped Gonzalez again. The fight was stopped 2:52 into the round.

"I wasn't trying to hurt him," Maynard said. "But he came at me and I had to slow him down. I was just trying to get loose."

Maynard then waited in the wings to watch Romero, the defending Pan Am champion. "I'm here to win the gold medal and I've got to go through the Cuban to get it," Maynard said.

The 6-foot Banks, of Chicago, had a height advantage over the 5-7 Cristofalo and used his reach to score consistently.

Banks, who also is notoriously confident and has frequently said he has little competition here, claimed it was a good opening bout. Banks has a previous victory over Mesa, in a U.S.-Cuba dual meet.

Swimming:

The United States enjoyed the same kind of success at the pool that it had in track and field. But it was much less expected.

This group of U.S. swimmers had been dubbed the B team before the competition even began, because many of the U.S. national champions, including Matt Biondi and Janet Evans, are in Brisbane, Australia, at the Pan Pacific championships. {Story on Page F6.}

Still, the Americans won gold medals in four of five events this afternoon, set two Pan Am records, and left with nine medals in a spirited we'll-show-you-how-good-we-are display.

Jeff Kubiak, a late-blooming Venice Beach, Calif., lifeguard, set a Pan Am record in his first international competition by finishing the 200-meter breaststroke in 2:17.62.

Mike Barrowman, from Potomac, Md. and the Rockville-Montgomery Swim Club, broke Steve Lundquist's Pan American mark set in 1983, but Barrowman's 2:19.29 -- in his first international competition -- was good enough only for a silver medal.

Kubiak, who at 22 is a relative senior citizen in his sport, had won seven national Division II titles at Cal State-Northridge.

Janel Jorgensen, a senior at Ridgefield (Conn.) High School, swam the 100-meter butterfly in 1:01.28 -- a personal best -- to narrowly beat Pittsburgh's Kristen Elias.

"We have been hearing a lot about being the B team," Jorgensen said. "We don't think it's true. The difference between the first- and fourth-place finishers {at the Nationals} is a matter of one-tenth of a second."

In other swimming finals, Paul Robinson of Richardson, Tex., won the gold in the 400-meter freestyle in 1:55.37. Scott Brackett, a recent Arizona State graduate, took the bronze.

The U.S. men easily won the 4x400 meter freestyle relay, in a Pan Am record 3:19.97. Canada and Brazil finished second and third, respectively.

Gymnastics:

Olympic gold medalist Scott Johnson led the U.S. men's team to a gold medal, setting a Pan Am record. The United States, breaking the previous team record by five points, beat Cuba 577.05 to 574.10. Johnson, 25, of Lincoln, Neb., scored a 9.85 on horizontal bar and a 9.80 on rings and led the individual standings over Felix Aguilera of Cuba by 117.30 to 116.00.

Brazil won the bronze medal with 550.80 points.