The Greco-Roman field is loaded, as four past Olympic medalists won national titles and will seek a spot on the U.S. World Team that will compete in New York City in September.    The team will be set at the World Team Trials at the Cintas Center at Xavier University in Cincinnati, Ohio, June 22-24. Olympic medalists Rulon Gardner, Matt Lindland, Garrett Lowney and Dennis Hall provide an all-star setting for a competitive Greco-Roman field.    119 pounds     Jeff Cervone of the Air Force claimed his first U.S. Nationals title in Las Vegas, defeating veteran two-time Olympian Shawn Sheldon in a close overtime battle in the national finals. After many years battling for position in this weight, Cervone hopes to peak in Cincinnati. Sheldon, who won a World silver medal in 1991, is a native New Yorker looking to compete in his home state at the World Championships.    The last two Olympians for the USA, 1996 Olympic silver medalist Brandon Paulson and 2000 Olympian Steven Mays, did not compete in Vegas, but both indicated they may enter in Cincinnati. Placing third at the U.S. Nationals was college star Chris Williams of Michigan State. A pair of young wrestlers from the USOEC resident program in Michigan, Nathan Piasecki and Joe Espinoza, placed fourth and fifth in Las Vegas. Also earning qualifying spots at nationals were Michel Santos and Sean Kim.     127.75 pounds    The Wisconsin War has continued, as Olympians Dennis Hall and Jim Gruenwald renewed their rivalry in Las Vegas. Gruenwald defeated Hall in the Olympic Trials finals in Dallas last year, and placed fifth at the Sydney Games. Hall is one of the sport's best ever, with a 1996 Olympic silver medal, a 1995 World gold medal and a 1994 World bronze medal. Hall turned the tables back, winning his 10th straight national title, and tossing Gruenwald for five points in the U.S. Nationals finals.      High school sensation Cam Jones, who has been an age-group star, placed a strong third in Las Vegas, losing only to Hall. Veteran Josh Fox claimed fourth place, his best performance to date. Lindsay Durlacher, who usually competes at 119 pounds, placed fifth at the higher weight. Also qualifying through Las Vegas were Jason Harless and Brady Jones. Armed Forces champion Duaine Martin, who has been a Team USA member many times, qualified for the Challenge Tournament, and will be a major force if he enters in Cincinnati.    138.75 pounds     Claiming a third career U.S. Nationals title in Las Vegas was Kevin Bracken, who placed sixth at the 2000 Olympic Games. Bracken defeated young U.S. Marines star James Shillow in the finals. Shillow, the Armed Forces champion, had his best performance ever. Glenn Nieradka, a 1999 U.S. Nationals champion and 2000 Olympic Trials runner-up, placed third. All three of these athletes are capable of earning a U.S. team spot.    U.S. Olympic Training Center resident athlete Joe Warren has emerged as a force with his fourth place finish. Veterans Glenn Garrison and Jason Tolbert qualified for the Challenge Tournament by placing in Las Vegas. University Nationals champion Darnell Lollis placed seventh at the U.S. Nationals, moving up from 127.75 pounds this season.    152 pounds    A new national champion was crowned in Las Vegas, as U.S. Marines veteran Marcel Cooper won the gold medal. Cooper has been a runner-up a number of times, and reached the top after many years of battling among the top athletes. He defeated surprise finalist Steven Woods of the Air Force, who also has paid his dues and continued to improve. 2000 Olympian Heath Sims was upset in the quarterfinals at the U.S. Nationals by Brian Van Hoven of the U.S. Marines, but battled back to place third, beating Van Hoven in the bronze-medal bout.    Veteran Keith Wilson placed fifth in Las Vegas, and remains a threat. Two-time U.S. World Team member Chris Saba placed sixth, but has the experience and skills to be a finalist. Also qualifying through the nationals was Oscar Wood. Expected to join the Challenge Tournament are University Nationals champion Matt Goldstein and 2000 Junior World medalist Joe Privatere, along with veteran Herb House.    167.5 pounds     Winning his second career U.S. Nationals title in Las Vegas was Keith Sieracki, who won his first national crown back in 1996. Sieracki is aiming to compete at his first World Championships, and looks to be in top form. He defeated exciting T.C. Dantzler in the finals. Dantzler had some explosive performances in Las Vegas, but has yet to solve Sieracki's attack. Veteran Dan Niebuhr, who moved back to this weight class last summer, placed a strong third at the U.S. Nationals.    Mike Mathers, from the USOEC resident program in Michigan, emerged as a contender with his fourth-place finish. Joey Clark of the U.S. Marines placed fifth, and his brother Jake Clark qualified earlier in the year at the University Nationals. Jake is expected to be a serious challenger for a spot in the finals. College star Carl Fronhofer, who competes at Pitt, has been a top star on the age-group and Senior levels. U.S. Marines veteran Keith Barkers claimed the final spot in the Challenge Tournament by placing seventh.    187.25 pounds    2000 Olympic silver medalist Matt Lindland successfully moved up in weight class from 167.5 pounds, winning the U.S. Nationals and claiming the Outstanding Wrestler award. In the finals, he scored an exciting come-from-behind win over  2000 Olympian Quincey Clark. This new battle of Olympians could be tremendous if renewed in the future. Veteran two-time Olympian Dan Henderson returned as a top challenger with a third-place finish in Las Vegas.    Armed Forces champion Aaron Sieracki of the Air Force placed fourth and is a strong contender. 1999 NCAA champion Brad Vering of Nebraska, who took a year off from Greco-Roman last year prior to his senior year in college, returned with a solid fifth-place finish. Ethan Bosch, the Olympic Trials runner-up last year, qualified for the Challenge Tournament by placing sixth. Also qualifying was James Meyer. Team USA member Chael Sonnen did not compete in Las Vegas due to injury, but is expected in Cincinnati. University Nationals champion Jake Clark is expected to drop to 167.5 pounds.    213.75 pounds    Olympic bronze medalist Garrett Lowney won the U.S. Nationals title in his first Greco-Roman tournament since his glory in Sydney. He also was able to drop down to 213.75 pounds successfully, in spite of wrestling all season as an All-American heavyweight for the Univ. of Minnesota. Lowney defeated veteran Jason Loukides of the Army in the finals, the best finish of his career. Kevin Vogel, who has competed at 167.5 pounds and 187.25 pounds in recent seasons, jumped up to this class and placed an impressive third.    Ross Thatcher, who competed in college at Penn State, made his first impact on the Senior national scene by placing fourth. The U.S. Marines swept the next three places at the U.S. Nationals, with Al Sankey, Tipton Peterson and David Workman all qualifying for the World Team Trials. Among the other qualifiers are Brian Kraemer, the University Nationals champion, and Dominic Black, the Armed Forces champion. Black, also the U.S. Nationals freestyle champion, is not expected to compete in Greco-Roman at the World Team Trials.    286 pounds     Olympic champion Rulon Gardner has returned to competition successfully, winning the U.S. Nationals in his first domestic test since claiming the gold medal in Sydney. In spite of a winter on the media circuit and limited training, Gardner was able to keep his edge over the rest of the field. 1999 World Team member Dremiel Byers made the finals against Gardner, losing a tight 1-0 match, and their rivalry may continue in Cincinnati. Byers was USA Wrestling Greco-Roman Wrestler of the Year in 1999.    Brian Keck returned to the amateur mats in Las Vegas and placed third. Young stars Paul Devlin and Andy Bowlby placed fourth and fifth in the U.S. Nationals respectively. Bowlby was also the University Nationals champion. Corey Farkas placed sixth in Las Vegas, but has the ability and experience to challenge for a spot in the Trials finals. Colle