Diane Simpson had survived the national championships a few months ago and come out the winner. Friday night before 3,857 in the Salt Palace - a large crowd for U.S. rhythmic gymnastics - Simpson survived a challenge from second-place Marina Kunyavsky, a three-time national champion, and she survived a very unexpected dropping of the apparatus in the club competition. She even survived the post-meet press conference, saying she was looking forward to tonight's finale.

And then she fainted.Simpson was fine after a few minutes. She does faint occasionally, so this was not such a big deal.

But she had just been talking about how relaxed it felt to have gotten two-thirds of the way toward the Olympics and to still be in the lead. "I feel very confident," said the 19-year-old from Evanston, Ill., and the Illinois Rhythmics club. "I don't think there's any more training I could have done.

"I feel very relaxed after today's competition. I did very well at the national championships and finishd today, and that's 200 percent of the 300 percent of your score."

But she knows tonight's finale of the U.S. Olympic rhythmic gymnastics trials will be the toughest of all. That's when the top two finishers will earn trips to Seoul, Korea, and the Olympics, and the rest - with the exception of a nontraveling alternate - will go home.

With the national-championship score added into Friday night's score, Simpson has a 77.600 total.

Kunyavsky, of Los Angeles, clung to second at 77.450, and Michelle Berube, the only active American former rhythmic Olympian, had made a charge, closing the gap between herself and Kunyavsky about .3 of a point since the nationals. Berube, of Illinois Rhythmic, has 77.250 points going into tonight's meet. She's nearly a point ahead of fourth-place Alexandra Feldman.

Simpson knows another slip like the one she made with the clubs could really hurt tonight. Yet, she can't take it easy, can't water down like they do in artistic gymnastics when being safe is the better choice.

"I don't think you can be safe in rhythmic gymnastics," Simpson said. "When you hold back, it shows."

Berube held back nothing as the event started Friday night. "I was so up for my first two events. I had the sparkle in my face. I could feel it," she said. She scored 9.7 in the rope event, and she scored 9.75 in the hoop event, both the highest scores of the event and both 1.5-2.5 better than she'd scored at the national championships.

Then came the 15-minute intermission. "I still felt really consistent, but I wasn't as calm and collected," Berube said.

She mishandled a club - but then so did several other competitors.

And even though Kunyavsky only scored 9.55 in clubs, down from 9.8 at nationals, she moved into a tie with Simpson for the overall lead after Simpson dropped both clubs for the first time in her memory. "I had a lot of adrenalin and was up for the routine too much - the throw was a little far forward," she said. "I didn't know our scores," Kunyavsky said. "We didn't have enough time to even change clothes." (Most competitors change leotards for each event.) All three leaders were within .3 of a point with one event, everyone's favroite, to go. Going into the ribbon, Kunyavsky and Simpson were at 67.8 and Berube at 67.5.

Simpson, saying she had no idea the others were so close, attacked the ribbon for herself. "I was just going to do the best routine I was capable of. My dream is to make the Olympic team," she said. "The idea is to assume your competitors are going to do their very best."

Berube came back from the clubs problem with a 9.75 in the ribbon.

Simpson tacked up a 9.8, the same as she'd gotten in nationals. "I knew I had to do a very good ribbon routine. I was looking forward to it," she said.

Had Kunyavsky, the night's last performer, gotten the same 9.8 she'd gotten at nationals, she'd have still been tied with Simpson, but she got 9.65 and actually dropped .05 point further behind in the totals.

"I made little mistakes," Kunyavsky said, "and this competition is much tougher than nationals in scoring."

That's because the judges are being extra careful to pick the best, the three agreed.

"I felt really good," Kunyavsky said, "but the 9.65 is really low for me."

RHYTHMIC NOTES - Tonight's start is at 7 p.m. A larger crowd is expected, but Friday's was thought to be the largest for a rhythmic competition in the U.S. except for the 1984 Olympics in Los Angeles, when the sport made its Olympic debut . . . Berube found the crowd "really receptive" to a sport most had never witnessed, particularly after the PA man said it was all right to clap and cheer . . . Large buildings such as the Salt Palace can generate their own wind currents that play with the lighter apparatus like the ribbons when they're thrown 35 feet into the air. Berube said the Salt Palace air seemed quite stable. "Pauley Pavilion in the '84 Olympics was absolutely the worst," she said. "Everyone was affected completely by that." . . . The men's and women's artistic gymnastics trials are Wednesday through Saturday in the Salt Palace.