Mayweather, 31, hanging up the gloves

Unbeaten welterweight champion Floyd Mayweather Jr. announced his retirement yesterday, with boxing's unofficial pound-for-pound king saying he no longer has the passion to fight. Mayweather, the World Boxing Council welterweight champ, made the abrupt announcement in a letter to select media members. The 31-year-old former US Olympian (39-0, 25 KOs) hasn't fought since beating Ricky Hatton last December, but was widely expected to fight Oscar De La Hoya in September in a rematch of the richest fight in boxing history. "This decision was not an easy one for me to make, as boxing is all I have done since I was a child," said Mayweather, the son and nephew of three of the sport's top trainers. "However, these past few years have been extremely difficult for me to find the desire and joy to continue in the sport."

Defending 100-meter Olympic gold medalist Justin Gatlin, who sold himself as the kind of athlete who didn't have to cheat to win, joined Marion Jones and Ben Johnson on the list of tainted champions. Gatlin's appeal to the Court of Arbitration for Sport on doping charges was rejected, three weeks before the United States holds its Olympic trials. The three-man CAS panel unanimously upheld the four-year ban given to the 26-year-old sprinter earlier this year by another arbitration panel. "I will continue to fight for my right to participate in the great sport of track and field in a time frame shorter than four years," Gatlin said in a statement . . . Tirunesh Dibaba of Ethiopia broke the women's world 5,000-meter record with a time of 14 minutes 11.15 seconds at the Bislett Games in Oslo. Dibaba shattered the previous record of 14:16.63, set by countrywoman Meseret Defar last year at Bislett Stadium. In the men's featured race, Olympic and world champion Jeremy Wariner won the 400 in a world seasonal best of 43.98 seconds . . . Brigham Young freshman heptathlete Chelsi Petersen was killed in a car collision in Provo Canyon, Utah.

Yankees co-chairman Hank Steinbrenner said he wants to re-sign general manager Brian Cashman, whose three-year deal ends after this season. "I've been thinking about it for a while," Steinbrenner said. He spent time with Cashman this week during the 2008 amateur draft, and said the GM is interested in staying with the team . . . Yankees reliever LaTroy Hawkins began serving a three-game suspension after his penalty was upheld by the commissioner's office. Hawkins was disciplined for throwing at Baltimore's Luke Scott last month . . . Righthander Sidney Ponson, who seemed to have his career back on track, was designated for assignment by the Texas Rangers in a surprise move. General manager Jon Daniels was vague about the reasons for the decision, saying Ponson had been dumped "for disrespecting teammates and club personnel."

Concerned that a second tenure as the Bulls' coach would spoil their friendship, Doug Collins told team chairman Jerry Reinsdorf to look elsewhere to fill Chicago's vacant post during a phone conversation. "I called Jerry this afternoon and said, 'Let's move forward and make sure we stay the friends that we have been for 25 years,' " said Collins, who coached Chicago from 1986-89 . . . In the WNBA, Asjha Jones sank a jump-hook with 19.7 seconds remaining and the host Connecticut Sun rallied from a 5-point deficit in the final 1:39 to defeat the Minnesota Lynx, 78-77 . . . Shameka Christon scored 19 points to help the host New York Liberty hold off the Houston Comets, 81-73 . . . Becky Hammon's 20 points led the San Antonio Silver Stars to a 63-52 win over the visiting Washington Mystics . . . Jia Perkins and Dominique Canty each scored 16 points as the visiting Chicago Sky beat the Atlanta Dream, 86-72 . . . Michael Phelps swam the world's fastest 100-meter butterfly of the year (51.04 seconds) at a meet in Omaha, beating world record-holder Ian Crocker's previous 2008 best of 51.32 . . . The Philadelphia Flyers acquired defenseman Danny Syvret from the Edmonton Oilers for forward Ryan Potulny . . . Galaxy star Landon Donovan (groin strain) is back on the roster for the United States soccer team's exhibition game against Argentina tomorrow at Giants Stadium in East Rutherford, N.J., and the 26-year-old can become the fourth-youngest player in the world to make 100 international appearances.