OMAHA, Neb. (OSU Athletics ) - Oklahoma State will be the favorite, but four other teams have their eyes on the trophy when the Big 12 Championships begin at the Qwest Center in Omaha, Neb., on Saturday.    Oklahoma State has won six of the previous eight titles with Oklahoma winning the two that OSU didn't. The Cowboys have yet to win three consecutive Big 12 titles, and have not won three consecutive conference titles since 1996-98, which included the final year of the Big Eight.    This year, however, could be the year that Oklahoma State is knocked off in the conference meet. Four of OSU's five Big 12 duals were not decided until after the final match. The Sooners have challenged the Cowboys twice, and it took a Steve Mocco major decision for OSU to beat Nebraska by one point.    Iowa State needed a bonus point victory from 125-pounder Grant Nakamura for the Cyclones to at least earn a tie, but Nakamura was upset by Coleman Scott.    "We want to qualify 10 competitors for the NCAA Championships, and it is going to be a tall order," Oklahoma State head coach John Smith said. "We will have to wrestle better than we have all year."    Oklahoma State, Oklahoma, Nebraska and Iowa State could all take home a Big 12 Championship on Saturday night, with Missouri looking to challenge as well. Oklahoma State has the top seed in half of the weights, while Iowa State has three individuals favored to win the Big 12 Championship.    "We have a better tournament team than a dual team this year," Missouri head coach Brian Smith said. "That is the opposite of past years. We are wrestling at our best right now and are excited about out chances for the tournament."    "I think the national champion will come out of the Big 12 Championships," Iowa State head coach Bobby Douglas said. "There are five to six teams that could win the NCAA championship, and this year's champion could depend on injuries."    Every bracket has at least one wrestler ranked in the top five except for the 133-pound weight class. The most exciting tournaments will be at 141 and at 165. The Big 12 has three wrestlers represented in the top four in the country, and four wrestlers are ranked in the top 10 at 165.    "The toughest weight class in the Big 12 might be 165 or 141 from the top three guys in both of those classes," Nebraska head coach Mark Manning said.    There will also be highly anticipated rematches. Ben Askren won the Big 12 title last year at 174, but top ranked Chris Pendleton would like to take it back. Zack Esposito and Matt Storniolo had two good matches this season at 149. Travis Pascoe helped Nebraska upset Iowa State by defeating third-ranked Kurt Backes.    The Big 12 Championships will serve as a preview for the NCAA Championships as many of the top wrestlers in the country will be competing in what should be several exciting matches.    "We have been hearing what great things about what Omaha has been doing, and it ought to be a great meet," Oklahoma head coach Jack Spates said.