LAS VEGAS - Patricia Miranda, an Olympic bronze medalist in 2004, came into this year's U.S. Olympic trials as the clear favorite in the 105.5-pound class of women's freestyle wrestling. Clarissa Chun had other plans.In a major upset Friday night, Chun beat Miranda in the first two matches of their best-of-three final series to clinch a 2008 Olympic berth. The 4-foot-11 Chun leaped into the arms of her coach, Keith Wilson, after her victory at the Thomas & Mack Center.Chun was beaten by Miranda in the finals of the 2004 trials. She lost to her this year at U.S. Nationals. Was she as shocked by Friday night's outcome as most others in the building?"I am and I'm not," said the 26-year-old native of Hawaii, who trains with USA Wrestling in Colorado Springs."I knew that I could do it. I just really had to do it. I had to just grit my teeth and just do it. I'm so excited and happy."While Miranda had a bye into the final, Chun had to first win the nine-wrestler Challenge Tournament Friday afternoon. Seeded third in the tournament, Chun defeated fourth-seeded Mary Kelly of Gaffney, S.C., in the final.At U.S. Nationals this year, Miranda beat Chun in a tight match in the semifinals. Miranda went on to a national title, which gave her the bye into the finals here Friday night. Chun placed fourth at nationals. That semifinal defeat gave Chun confidence."It was controversial. It was a very close match. Some people say I won it," she said."It didn't turn out that way, but I was really confident from that, believing in myself that I could do it. I was like, 'This is my time. I've been sitting on the back burner for way too long.' "The format for international wrestling has undergone major change since the 2004 Olympics.Instead of wrestling six-minute matches with two three-minute periods, each match now consists of potentially three periods of two-minutes each.Each period is scored independently. The first wrestler to win two periods wins the match. No points carry over from period to period. Each period is a mini-match unto itself. In their first match Friday night, Chun beat Miranda 4-0, 0-6, 3-1. In the third period, Chun got her winning points in the final seconds.In the second match, Chun won 1-0, 3-1. Trailing 1-0 in the second period, Chun scored the three points that made the difference in the final 10 seconds. She executed a double-leg takedown that exposed Miranda's back to the mat for the three-point move.Chun said her coach had told her to "be stubborn on the mat, don't give up if you're down by one."She didn't give up Friday night. "I was just in the moment, and it happened, and I'm so glad," said Chun.Also clinching Olympic berths Friday night in the other three women's weights eligible for the Games were Marcie van Dusen of Lake Arrowhead, Calif. (121 pounds), Randi Miller of Arlington, Tex. (138.75) and Ali Bernard of New Ulm, Minn. (158.5).The lone Olympic berth in men's wrestling decided Friday night went to Spenser Mango of Florissant, Mo., in the 121-pound class of Greco-Roman.