In a fight that almost didn't happen because Corrales (40-4) couldn't make the weight, Casamayor (34-3-1) won the vacated title and the rubber match between the two fighters.
Casamayor won, 116-111, on one scorecard and 115-112 on a second. A third judge had Corrales ahead, 114-113. The Associated Press had Casamayor winning, 116-112.
Corrales had to give part of his $1.2 million payday to Casamayor so the fight would proceed after he didn't make weight. He was also fined $240,000 by the Nevada Athletic Commission.
Corrales said he would probably move up to welterweight.
"I overstayed my time and that is that," he said of his time as a lightweight.
Nikolai Valuev retained the WBA heavyweight championship, stopping Monte Barrett in the 11th round in Rosemont, Ill.
The 7-foot, 328-pound Valuev (45-0, 33 knockouts) knocked down Barrett (31-5) twice in the 11th, and the fight was stopped 2:12 into the round.
Federer Reaches Final
by Stopping Becker in Tokyo
Top-ranked Roger Federer cruised to a 6-3, 6-4 win over Benjamin Becker in Tokyo to advance to his first Japan Open final.
Federer will meet Tim Henman in today's final after Henman posted a 6-4, 7-6 (5) win over ninth-seeded Lee Hyung-taik.
In the women's semifinals, top-seeded Marion Bartoli beat Camille Pin, 6-0, 6-1, to set up a final with Aiko Nakamura, who defeated Chan Yung-jan, 7-6 (3), 2-6, 6-4.
Fourth-seeded Nadia Petrova, chasing her fifth title of the season, defeated second-seeded Svetlana Kuznetsova for the first time in three meetings, 6-2, 1-6, 6-4, to reach the Porsche Grand Prix final in Stuttgart, Germany.
Unseeded Tatiana Golovin is the other finalist, beating fifth-seeded Patty Schnyder, 6-1, 5-7, 7-5.
Jurgen Melzer reached the final of the Open de Moselle, beating Marc Gicquel, 7-6 (3), 6-3, in Metz, France.
He will face third-seeded Novak Djokovic, the only seeded player to reach the tournament's quarterfinals. Djokovic beat Sebastien Grosjean, 6-7 (4), 7-6 (1), 6-3.
Wild card Iroda Tulyaganova upset sixth-seeded Olga Poutchkova, 6-4, 6-0, to reach the finals of the Tashkent Open in Uzbekistan.
Tulyaganova will meet Sun Tiantian, who beat Victoria Azarenka, 7-5, 6-4.
Officials of the 11th annual Andre Agassi Grand Slam of Children charity dinner estimated that this year's event raised $8.6 million. The event, held at the MGM Grand Arena in Las Vegas, raised $3.75 million in an auction. The rest came from dinner and corporate sponsors.
Football Player, 17, Dies
After Collapsing in Game
Fermin Vialpando, a 17-year-old high school football player, died shortly after collapsing during a game in Colorado Springs.
Vialpando, a 6-foot-1, 210-pound center for Harrison High, was running down the field in the third quarter Friday night when he collapsed, The Gazette newspaper reported.
Vialpando had a heart condition, said Dawn Miller, El Paso County deputy coroner. Further tests were needed to determine the cause of death. His mother, Sundae Vialpando, had told the Denver Post on Saturday that he had no known health problems.
Duke's lacrosse team returned to the field, playing a series of scrimmages against opposing teams at a charity event on Long Island, N.Y.
Following allegations that three players raped a stripper at a team party, the team's season was canceled in April, and only when the players wrote a new code of conduct, earning the university's approval, was the program reinstated in June.
The defending champion U.S. women lost to France, 45-42, in team sabre at the fencing world championships in Turin, Italy.