Defending champion Florida University, Ohio State, Kansas and North Carolina were seeded No. 1 in the four regional brackets of the U.S. college basketball championship tournament, earning those spots Sunday by winning their conference titles. The 65-team tournament begins Tuesday night in Dayton, Ohio, with a play-in game between Florida A&M and Niagara, the two lowest-ranked teams. Starting Thursday afternoon, the month-long, knockout tournament begins, and turns average office workers into avid gamblers. Among the more surprising omissions from the field was 2003 champion Syracuse. Drexel, Kansas State, Air Force and West Virginia also were left out. “We actually had 104 teams that had won 20 or more games, and that was more than the previous record of 78,” tournament selection chairman Gary Walters said. A year after George Mason became the nation’s favorite underdog, mid-majors won’t get a great chance for another run. Only six of them — down a couple of spots from last season — were included in a field dominated by the power conferences. George Mason, which lost to Virginia Commonwealth in the Colonial Athletic Association championship, was not among them. The committee chose Old Dominion over Drexel because of the Monarchs had a better inter-conference record by a significant margin. George Mason beat Old Dominion in the Colonial tournament. The Atlantic Coast Conference sent seven teams in the tournament, up from four last year, highlighted by former national champions Duke, North Carolina and Maryland. The Big East, Big Ten and Pac-10 sent six. Going by the top seeds, the East is the toughest of the regionals with North Carolina and Georgetown, the regular season and tournament champions of the ACC and Big East, as the top two seeds. Washington State, the regular season runner-up in the Pac-10, is the No. 3 and Texas, which lost in overtime to Kansas in the Big 12 title game on Sunday, is the best of the No. 4s. Florida, which won the gridiron football championship in January, will begin its bid for another basketball title in the Midwest region with a game Friday against 16th-seeded Jackson State in New Orleans. Wisconsin got the No. 2 seed in the Midwest and will play No. 15 Texas A&M-Corpus Christi. Other games in the region are: No. 3 Oregon vs. No. 14 Miami of Ohio, No. 4 Maryland vs. Davidson, No. 5 Butler vs. No. 12 Old Dominion and No. 6 Notre Dame vs. No. 11 Winthrop, which has an 18-game winning streak and No. 7 UNLV vs. No. 10 Georgia Tech, and No. 8 Arizona vs. No. 9 Purdue. In the West, Big 12 champion Kansas (30-4) opens against the play-in winner Friday in Chicago. UCLA, with the most NCAA men’s basketball titles in history, became a No. 2 seed after losing its first game in the Pac-10 tournament to California and open against Weber State. Also in the West bracket, it will be: No. 3 Pittsburgh vs. No. 14 Wright State, No. 4 Southern Illinois vs. No. 13 Holy Cross and No. 5 Virginia Tech vs. No. 12 Illinois. Coach Mike Krzyzewski and Duke got the No. 6 seed after losing to North Carolina State in the first round of the ACC tournament. The Blue Devils will play No. 11 Virginia Commonwealth. No. 7 Indiana plays No. 10 Gonzaga, and No. 8 Kentucky faces No. 9 Villanova. North Carolina (28-6) drew the top seed in the East by defeating N.C. State for the ACC title, and will make the short trip to Winston-Salem to play Eastern Kentucky on Thursday. Big East champion Georgetown is the No. 2 seed and takes on No. 15 Belmont. Also in the East, it’s No. 3 Washington State vs. No. 14 Oral Roberts; No. 4 Texas and star Kevin Durant against No. 12 New Mexico State; No. 5 Southern California vs. No. 12 Arkansas; No. 6 Vanderbilt vs. No. 11 George Washington, No. 7 Boston College vs. coach Bobby Knight’s 10th-seeded Texas Tech, and No. 8 Marquette vs. No. 9 Michigan State. Ohio State (30-3) beat Wisconsin to win the Big 10 tournament and its No. 1 seed in the South. The Buckeyes play No. 16 Central Connecticut State on Thursday in Lexington, Ky. Other games in the South include coach John Calipari and No. 2 Memphis against No. 15 North Texas, making its first NCAA tournament appearance since 1988; No. 3 Texas A&M vs. No. 14 Pennsylvania; No. 4 Virginia vs. No. 13 Albany, N.Y.; No. 5 Tennessee vs. No. 12 Long Beach State; No. 6 Louisville vs. No. 11 Stanford; No. 7 Nevada vs. No. 10 Creighton and No. 8 BYU vs. No. 9 Xavier.