By the time they were finished Monday night in the rainy U.S. Olympic Track and Field Trials in Indianapolis, Carl Lewis and Larry Myricks had staged the greatest long jump duel in history, but in the end the result was the same. Lewis, the defending Olympic champion, had won his 54th consecutive long jump competition.

Lewis leaped 28-9 - just 11/4 inches short of his sea-level world record - to edge Myricks, who had a best mark of 28-81/4. (Mike Powell was third, at 27-51/2.) But for once, it wasn't Lewis vs. the tape measure. Lewis had Myricks to contend with, and on this night that was plenty. Three times, each man leaped beyond 28 feet, a distance only five men have ever surpassed, and three times the lead changed hands.Myricks opened with a mark of 27-8, Lewis answered with 27-41/2, and then Myricks raised the stakes, going 28-03/4. Just as Lewis took his place at the end of the runway for his second attempt, a driving rain began to fall, but even as most of the 11,000 fans raced from the stands for shelter, Lewis remained where he was. "I was afraid it would rain for two or three hours, so I wanted to get a good jump in," he said. He did, going 28-21/4.

When the competition resumed a half-hour later, Myricks picked up where he left off, leaping 28-81/4, a meet and personal record and a mark that has been bettered by only three men. Now Lewis was pressed. "Larry jumped within two inches of my personal best," said Lewis. "I had to dig down deep to win." Lewis answered with his winning leap of 28-9.

On his final three attempts, Myricks went 28-03/4, 26-51/2 and then fouled on what appeared to be a near-record leap. "It looked like it was out near the world record," said Myricks. "I fouled by five or six inches."

Lewis, after fouling on his third attempt, leaped 28-53/4 and then bailed

out midway through his final attempt. Afterward, Lewis said only his busy schedule prevented him from a bigger performance. Earlier in the week, he had sprinted through four rounds of the 100-meter dash, thrice running under 10-flat. Earlier Monday he produced the fastest times in the first and second rounds of the 200 - 20.32 and 20.03.

"There's no question that it has to take something out of you," he said. ". . . My objective coming here was to make the team in three events. I've made it in two, and I'm confident about the third."

As has become a regular occurence at this meet, the trials produced another day of superb, even stunning, performances.

Steve Lewis, a 19-year-old freshman at UCLA, set a world junior record (for 19-year-olds and younger) of 44.11 to win his semifinal heat of the 400-meter dash. He smashed his own junior record of 44.61 set the previous day. The time, the second fastest ever at sea level, also makes him the fourth fastest performer in history. Lewis' UCLA teammate, Danny Everett, finished second in 44.32, and Butch Reynolds won the other heat in 44.65. All of which promises a sensational race in Wednesday night's final, and a serious assault on Lee Evans' elusive 20-year-old world record of 43.86.

Johnny Gray, the American record holder, ran away with the 800-meter final. He busted through 400 meters in 50.2 and opened a 15-meter lead on the backstretch. He held on well enough to clock 1:43.96 and withstand a strong homestretch run by runnerup Mark Everett (1:44.46) and Tracy Baskin (1:44.91). Afterward, Gray, who ran a victory lap with his two children while waving a homemade "Say-no-to-drugs flag," announced, "I want an Olympic medal. Even if it's a copper medal." Or how about silver, which was also the color of his racing shoes?

In other finals Monday:

- Despite ideal conditions - cool and windless - the 10,000-meter final was slow and tactical. Bruce Bickford made a big move to break away from the field with just under two miles to go and went on to win with a time of 29:07.35. Steve Plasencia made a late run at Bickford and finished a close second in 29:08.58. Pat Porter pulled away from Mark Nenow over the final 250 meters to finish third in 29:09.92.

- Diane Dixon won the women's 400-meter dash in 50.38. Denean Howard was second in 50.40, and Valerie Brisco, the defending Olympic champion, was third in 50.53.

- Ken Flax set a meet record of 253-6 to win the hammer.

- Other notes: Joe Dial, the American record holder in the pole vault, no-heighted in Monday's qualifying round . . . Alonzo Babers, the 1984 Olympic 400-meter gold medalist, finished fifth in his semfinal heat and failed to advance to the finals. He has spent most the past four years flying jets for the U.S. Air Force.