NORMAN — It began with Oklahoma-Texas on Oct. 11. It will culminate with No. 2 Texas Tech at No. 5 OU next Saturday. In no year has the Big 12 had so many matchups that captured the attention of the nation. OU-Texas, Oklahoma State-Missouri, Missouri-Texas, OSU-Texas, Texas-Texas Tech and OSU-Texas Tech. Games that carried national title implications on both sides. None, however, looms bigger than Tech-OU, with the winner taking a big step toward reaching the national championship. Not only will the game be shown by ABC to a national audience, but ESPN GameDay is likely to broadcast from Norman. The game will also feature quarterbacks Sam Bradford and Graham Harrell, two of the frontrunners for the Heisman Trophy. For Tech, it’s the biggest game in school history. Win, and the Red Raiders are all but assured of reaching the school’s first Big 12 Championship, and potentially the school’s first national championship, too. For the Sooners, it’s the biggest home game since No. 1 Nebraska came to Norman in 2000. OU defeated the Cornhuskers 31-14 on the way to the school’s seventh national championship.