Sunday morning's first session in the U.S. Olympic Team Trials at the RCA Dome in Indianapolis, Ind. had five Challenge Tournament winners defeat U.S. National champions.    Three of the Challenge Tournament champions to win the first match of the Championship series came in Men's Greco-Roman, where 1996 Olympic silver medallist Dennis Hall (55 kg), 2000 Olympic bronze medallist Garrett Lowney (96 kg) and 2000 Olympic gold medallist Rulon Garnder (120 kg) all topped their U.S. National champion opponents.    Hall gave up a two points on a gut wrench against fellow 1996 Olympic silver medallist Brandon Paulson, but stepped over immediately to score two points of his own. The two wrestled a scoreless second period and went into overtime. Paulson locked first in the clinch, but five seconds into overtime, he was hit for a caution for fleeing the mat, giving Hall a 3-2 victory.    Lowney topped Justin Ruiz in a 1-1 referee's decision, avenging his only defeat to Ruiz from last month's U.S. Nationals in Las Vegas. Ruiz went up 1-0 with a hand to hand gut wrench late in the first period, but the two didn't score in the second period, leading to clinch to start overtime.     Ruiz broke his lock 19 seconds into overtime and the score remained tied 1-1, but Lowney was awarded the decision based on Ruiz's lone caution.    Much of the crowd stayed to watch the final match of the session, Gardner's 2-1 overtime victory over World champion Dremiel Byers. Garnder went up 1-0 at the start of the second period from the clinch, where Byers broke his lock.     Byers tied the match when Gardner was penalized a point for failing to start from the bottom par terre position properly. Like many of their previous matches, the bout went to overtime and Gardner earned the go-ahead point 55 seconds into overtime when Byers tried a head throw and ended up bailing out, giving Gardner the one-point takedown.    At 66 kg, U.S. National runner-up Oscar Wood bulled over 2000 Olympian Kevin Bracken and got the only pin of the Championship Series in Greco-Roman at 1:47 of the first period.    In Women's Freestyle, Tela O'Donnell pinned 2003 World silver medallist Tina George with three seconds left in the bout. O'Donnell led 3-2 going into the second period and after George tied the match with a takedown, O'Donnell took back the lead and then headlocked George to her back in the final seconds to secure the fall.    At 72 kg, 2003 World silver medallist Toccara Montgomery rallied from a 5-0 deficit to beat 2003 World champion Kristie Marano 9-6 in overtime. Montgomery barreled two double-leg takedowns in the second period to get within 6-4 and tied the match with 30 seconds left in regulation with a two-point exposure. In the extra period, Montgomery again shot in with a double-leg, dumping Marano on her back at the edge of the mat for three points and the victory.    Cael Sanderson was the lone Challenge Tournament winner in men's freestyle to beat a U.S. National champion, beating Lee Fullhart 3-1 at 84 kg. In each previous match during the trials, Sanderson scored in the first minute on a low-single and Sunday's match with Fullhart was no exception. Sanderson scored his first takedown 15 seconds into the match and added another a minute later to go into the break up 2-0. Fullhart's lone point was earned on a caution against Sanderson.    At 55 kg, 2003 World team member Stephen Abas scored four takedowns and a reversal to beat 2000 Olympic silver medallist Sammie Henson 5-3. Henson got within a point at 4-3 with 40 seconds to go, but Abas quickly turned the tide, scoring a reversal two seconds later and held on for the victory.    2003 World team member Daniel Cormier scored the only fall in the Men's freestyle, bullying 2002 world team member Tim Hartung, taking him to his back and securing the pin at 4:47. Cormier jumped to a 6-0 lead on four takedowns and a two-point gut wrench in the first period.     Other winners were:  Men's Freestyle: Eric Guerrero (60 kg) beat  Mike Zadick 3-1; Jamill Kelly (66 kg) beat Jared Lawrence 4-1 in overtime; Joe Williams (74 kg) beat Joe Heskett 4-0, and Kerry McCoy (120 kg) beat Tolly Thompson 5-3.    Men's Greco-Roman: Jim Gruenwald (60 kg) beat Joe Warren 5-3; Darryl Christian (74 kg) beat Keith Sieracki 4-0; Brad Vering (84 kg) beat Jake Clark 5-1.    Women's Freestyle: Patricia Miranda (48 kg) beat Clarissa Chun 6-3 and Sara McMann (63 kg) had the only technical fall of the Championship Series, beating Alaina Berube 10-0 in 2:05.