World record holder Mike Powell won't compete in the long jump at the U.S. Olympic track and field trials next week because of a knee injury, ending his comeback bid at age 40.

Powell, who said last month he would try to make the U.S. team for the upcoming Athens Games, said yesterday in a statement given to the Associated Press that he hurt his knee jumping over a fence a few weeks ago while he was coaching at a track meet.

"It really was a fluke injury," Powell said. "I jumped down over a six-foot fence and landed awkwardly. The next day I had pain and swelling around my knee."

He tried to continue training but started developing problems in his hip and Achilles' tendon and wasn't healthy in time to make a qualifying mark for the trials, which start Friday in Sacramento.

"Naturally, I am very disappointed about the injury," Powell said. "Other than the injury, I am in great shape physically and mentally and was on track to make the Olympic team.

"But I believe everything happens for a reason. I could ignore the warnings and risk a lifetime injury, but it is not worth it. Although I would love to compete in the Olympics one more time, it is far more important to me to be able to play with my kids without the use of crutches or a wheelchair."

Powell wowed the world in Tokyo in 1991 when he set the world record with a jump of 29 feet 41/2 inches to break Bob Beamon's record. He and Carl Lewis battled against each other during the 1980s and '90s, but Powell never won an Olympic gold medal.

He came out of retirement once. In 2001, he returned at the U.S. championships after a four-year break but finished fourth at a wind-aided 26-7 -- nearly three feet off his world mark.

During his career, Powell won two Olympic silver medals, two world outdoor titles and six world indoor titles.

United, They'll Stand

North and South Korea will march together at Opening Ceremonies in Athens on Aug. 13.

"It shows that sport can unite and promote peace. It is wonderful to see the two national Olympic committees putting the Olympic values into practice in such a demonstrable way," International Olympic Committee President Jacques Rogge said in a statement yesterday.

The two Koreas said in February they wanted to march under the same flag, as they did in Sydney in 2000. The teams will enter together behind a flag depicting the entire Korean Peninsula.

They hope to field a unified team for the 2008 Games in Beijing.

British Cyclist Withdraws

Cyclist David Millar withdrew from the British Olympic team yesterday, one day after telling a French judge he used a performance-enhancing drug.

Millar, already barred from the Tour de France, admitted Thursday he used EPO, which works by boosting oxygen-carrying red blood cells.