It will be remembered as the night that Nadia Comaneci fell, and the Soviets rose again.

On an eventful, emotional, electrifying and sometimes controversial evening of gymnastics at the Olympic Games, the Soviet Union regained international women's team supremacy, and Romanian Comaneci took a puzzling fall from the uneven bars that seriously jeopardized her chances of repeating as the all-around gold medalist.

The talent-laden Soviet women -- who have won the team title in every Olympics since 1956, but were startlingly striped of the world championship by Romania in Fort Worth last December -- got sweet revenge tonight to the glee of a stomping, cheering chanting home crowd at the Lenin Sports Palace.

The Soviets knew that they had a virtual stranglehold on the team title going into the floor exercises, their last and strongest event, and they finished with a tour de force that brought the house down.

None of the six members of the Soviet team scored less than 9.9 in the floor exercises, and Yelena Davydova was brilliant in registering a perfect 10, as the home team took the gold medal with a total of 394.90 points.

The world champion Romanians, who were third after Monday's remarkably close and highly scored compulsory exercises, finished frustrated and unhappy in second place with 393.50 points. East Germany, which started the day in second, wound up with 392.55 points and the bronze medal.

East Germany's 15-year-old Maxi Gnauck -- who began tonight's optional exercises with a perfect 10 on the bars, and added a 9.8 on the balance beam, 9.95 in the floor exercises, and 9.9 in the vault -- leads the all-around standings with 39.675 points going into Thursday's finals.

Gnauck, who stands 4-foot-10 and weighs barely 71 pounds, performed her floor exercises to the taped strains of the song "Thoroughly Modern Millie." If she wins the all-around gold, succeeding Comaneci, they may have to change the name of the tune to "Thoroughly Modern Maxi."

It was a trying night for Comaneci, who has grown to 5-3 and 99 pounds from the tiny tot of 14 who captivated the 1976 Montreal Olympics with her grim-face perfectionism, hardly cracking a smile as she won three gold medals, a silver and a bronze.

With all eyes on her, since she was the last to perform in the first rotation, she began her heartbreaking evening with what appeared to be another flawless routine on the balance beam, her premier apparatus.

Photographers' shutters clicked movie cameras whirred, and the audience burst into spontaneous applause for her exquisite, confident moves on the beam. But her score was slow in coming to the electronic scoreboard because of a computer problem, and after five minutes only a 9.9 appeared. Whistles and catcalls filled the arena.

Romanian Coach Bela Karolyi was so infuriated that he ran halfway around the hall and charged the judges, waving a sheet of paper and arguing furiously. The Romanians later filed an official protest, but Karolyi knew immediately that this score was the harbinger of a long, exasperating night for his team.

Comaneci also scored 9.9 in the floor exercises and the vault to hold the all-around lead going into the final rotation, but then disaster struck.

She was performing on the uneven bars at the same time Natalia Shaposhnikova -- the leading Soviet woman gymnast, who is second to Gnauck in the all-around standings with 39.575 points -- was doing her floor exercises to the theme music from the old Billy Wilder movie, "One, Two, Three."

Comaneci had begun her routine on the bars with a new and complex element, and pulled it off without a hitch. "She was so happy about the start," a Romanian official said later, shaking his head sorrowfully, "that she lost her concentration for just a moment, and fell at one of the easiest parts."

Comaneci's hand slipped as she shifted from the higher to the lower bar, and she tumbled to the mat below as the crowd of 10,000 spectators, most of whom had been watching Shaposhnikova, gasped.

Comaneci scrambled back up and finished the last few seconds of her routine. Ever serious, she didn't seem to lose her composure at all, but she must have been aching inside. She was penalized half a point for her fall and still posted a 9.5, which means that she would have scored a perfect 10 save for the mishap.

With her slip, Comaneci also plunged to fourth in the all-around standings, behind Gnauck, Shaposhnikova, and fellow Romanian Emilia Eberle, who takes 39.525 points into Thursday's finals.

Davydova is fifth (39.500), and 22-year-old Nelli Kim of the Soviet Union -- winner of the gold medals for floor exercises and bars at Montreal, and the all-around champion at Fort Worth in the absence of the injured Comaneci and Shaposhnikova -- is sixth (39.475) and seemingly out of the running.

The gymnasts take half of their cumulative point totals after the compulsories and optionals into the all-around finals. Thus, for example, Gnauck goes into the finals with half of the 79.35 points she has amassed so far. Half of the scores already accumulated also count toward Friday's individual apparatus championships.

There were four 10s scored in the various apparatus tonight: Gnauck and Eberle on the uneven bars, Romanian Melita Ruhn in the vault and Davydova for her rousing floor exercise routine. But there was widespread dissatisfaction with the judging.

When Kim -- the popular Eurasian beauty who looks downright statuesque among her fellow gymnasts at 5-2 and 101 pounds -- received a score of only 9.75 for her two valuts, there were lusty boos.They were repeated fairly frequently throughout the evening.

Karolyi, who berates officials in the animated manner of an American basketball coach, was especially agitated. So were the several dozen Romanian spectators who sat in the front rows, cheering their team and waving their national flag.

But by the conclusion of the third rotation -- which ended with the spunky, ponytailed Shaposhnikova dismounting after a 9.8 performance on the beam and waving to all sides of the arena, it was evident the Soviet women's monopoly on the Olympic team title would continue.

If there were lingering doubts in anyone's mind, they were quickly dispelled in the floor exercises. Yelena Naimoushina, leading off for the Soviets, had the crowd howling and clapping rhythmically with her as she danced and somersaulted through a spirited, acrobatic routine.

She scored 9.95, and teammate Mariya Filatova follow with another 9.95. Then Davydova, an ascending 18-year-old from Leningrad, stole the show with a wonderfully athletic and snappy routine that began to the tune of "Gypsy Woman." Her 10 was followed by 9.9 routines from Stella Zakharova and Shaposhnikova, and a climatic 9.95 from Kim.

"We knew very quickly that there was no way we could win the team championship," said the disappointed Romanian official, "especially with the Soviets finishing with floor exercises, and the public making big noise and support for them. That is influencing the gymnasts, and the judges. You have a term for this in the United States.?"

Yes, indeed. It'd called "the home mat advantage."

In swimming, the Soviet Union picked up two more gold medals, the East German women continued their awesome domination and recorded another world record, and a Soviet diver had his apparent victory held up pending an appeal.

Aleksandr Portnov appeared to win the gold medal in the men's springboard diving, but a protest was lodged by the men who finished in the next three places, and officials of the international swimming federation, FINA, said that a final decision would not be made until Friday. The medals presentations were not held.

On the eighth of his 11 dives, Portnov attempted to reverse 2 1/2 somersault, which carries the maximum 3.0 degree of difficulty. He botched it, but came out of the water objecting to a Swedish judge that the crowd had distracted him. He was permitted to dive again, received 67 1/2 points from the all-Western judging panel (no Communist Bloc members), and won with a total of 905.025 points.

Portnov's complaint did not sit well with his rivals, however. second-, third- and fourth-place finishers Carlos Giron of Mexico, Franco Cognotto of Italy, and Falk Hoffman of East Germany filed a protest over the redive, which will go to an appeal jury. Stay tuned.

Meanwhile, the Soviets swept all three medals in the women's 200-meter breaststroke, won by Linda Kaciustye in 2:29.54 an Olympic record but short of her world record time of 2:28.36 for the event. Svetlana Varganova led by two seconds after 150 meters, but Kaciustye finished strongly, according to plan, and won by seven-hundredths of a second.

Rica Reinisch, 15, of East Germany set a world record in the 100-meter backstroke for the third time in four days, winning the gold in 1:00.86 over countrywomen Ina Kleber (1:02.07) and Petra Riedel (1:02.64).

Reinisch had tied East German Ulrike Richter's previous world mark of 1:01.51 in the first leg of a victorious 4x100 medley relay on Sunday, and bettered it by a hundredth of a second in a preliminary heat Tuesday.

Per Arvidsson 20, of Sweden and the University of California team, won the gold medal in the men's 100-meter butterfly. But his time of 54.92 seconds fell short of his world record of 54.15.

Arvidsson had finished a disappointing seventh in the 200-meter butterfly, and was off-form in the 100-meter qualification heats, but he rose to the occasion and gave Sweden its second swimming gold of the Games. The first was won unexpectedly by Bengt Baron in the 100-meter backstroke.

Once again, a triumph for the blue-and-gold sent Sweden's large press contingent scurring to the telephones at the grand and fast new Olympic Swimming Complex on Prospekt Mira ("Peace Avenue"). As a British writer once observed of the Swedish reporters who follow tennis star Bjorn Borg, "they are forever running to dictate stories that gurgle down the telephone wires like disappearing bathwater."