MINNEAPOLIS, FEB. 16 -- Tonya Harding, a 20-year-old figure skater who always seemed to fall in competition, today perfectly performed the most difficult program ever by a U.S. woman and won the national championship over favorite Kristi Yamaguchi.

Harding became the first American woman ever to complete a triple axel and flawlessly performed an incredible seven triples in all to win the long program and the title at the U.S. Figure Skating Championships at Target Center. She became the first U.S. woman ever to complete all six different triple jumps possible in a routine; Japan's Midori Ito is the only other one to do it.

Harding also became the second woman ever to receive a perfect technical merit score of 6.0 from a judge at a U.S. nationals. Janet Lynn received two 6.0s 18 years ago.

The judges duly noted the historical significance. Harding was ranked first by seven of the nine judges in today's competition; Yamaguchi, who fell once trying a triple salchow, received the other two first-place rankings. The long program counts two-thirds toward the final score; Thursday's original program accounted for one-third. Yamaguchi won eight of the nine judges' top rankings that night, but the overwhelming support for Harding today made her the overall winner. Nancy Kerrigan finished third. All three will compete in the world championships next month in Munich.

In tonight's final event, Elizabeth Punsalan and Jerod Swallow won the ice dancing title.

An upset is rare in figure skating, where the athletes' placings and pecking order are usually set in sedimentary rock. Judges, skaters and the entire U.S. figure skating community thought Yamaguchi, 19, who gave up pairs competition to devote herself to singles, could skate circles around anyone else in this country. And she was believed to be the nation's best jumper in a sport that has placed a premium on that skill by dropping school figures from competition.

There was considerable weight given to this theory today, especially because reigning world champion Jill Trenary of the United States is out with an ankle injury and Ito, the 1989 world champion and already the Olympic favorite, may miss the worlds because of jaw surgery.

The thinking was that if Yamaguchi won here, she probably would win in Munich and move into the Olympic year with imposing international credentials.

Seven spectacular triple jumps in four minutes changed everything.

Now Harding, who grew up in Portland, Ore., and has suffered with asthma most of her life, is the jumper of note in the United States.

"This makes me feel really good about myself that I can do something nobody else can do," she said.

Harding had never before made a world championship team when she skated onto the ice this afternoon. Her best finish in the nationals was third in 1989 (only two U.S. skaters qualified for the worlds that year) and she was seventh last year skating with flu.

As she practiced with Yamaguchi and three others in the final group before their programs began, she flew into a triple-axel. She fell. She went back down the ice, tried again and hit it. "I was thinking, 'Just concentrate,' " Harding said. " 'It's just another jump.' "

Harding performed her routine three skaters after Yamaguchi, who, wearing bright red, played the seductress from Samson and Delilah and darted through a sophisticated routine. She fell on the triple salchow midway through her program, but did complete six triples. She received all 5.7s and 5.8s for technical merit, all 5.8s and 5.9s for composition and style.

Excellent marks, but there was room for Harding.

Skating in spearmint green to the theme from "Batman," a piano rendition of "Send In The Clowns" and the rapper Tone Loc's "Wild Thing" (an eclectic mix if ever there was one), she quickly lifted through her first triple and moved toward the far end of the ice for her attempt at the triple axel 45 seconds into her program. She had tried it four other times in competition in the past year, without success.

This time, Harding flew high, spun three times and landed sharply as the crowd cheered wildly. "Yes!" she screamed out, pumping her fists.

Almost immediately, she told herself to settle down. She had more than three minutes to go.

" 'Wait a second,' " she said to herself. " 'Take it slow. It's not just the triple axel.' "

She had five more triples to accomplish. She nailed them all.

Her scores were tremendous: eight 5.9s and one 6.0 for technical merit and six 5.9s, one 5.8 and two 5.7s for composition and style.

"My horoscope said I was going to be perfect all week," Harding said. "I was counting on that."