Sprinter Maurice Greene of the United States celebrates as he crosses the finish line to win the gold medal in the 100 meters at the Olympics in Sydney, Australia. Greene announced his retirement Monday, citing nagging injuries.

Beijing ? Maurice Greene sprang a little surprise on Monday – he’s retiring.

The former Olympic and world champion cited nagging injuries for his decision, making the announcement halfway around the globe and not long after the Super Bowl had ended in Glendale, Ariz.

Traveling in China inspecting Olympic facilities with a group of contenders for Olympic gold, the 33-year-old Greene said injuries forced him to retire. Coaching and business interests in the U.S. now will be his focus.

“It’s a little sad for me, but it’s happy at the same time because I’ve had a great career. I’ve done a lot of great things,” Greene said in an interview with the Associated Press. “For the last couple of years, I’ve had nagging injuries that have stopped my training. So I think it’s better to just call it quits.”

Greene, a native of Kansas City, Kan., was the dominant sprinter of the late 1990s and into the new century. He set a world record for the 100 meters in 1999 and won the same sprint at the Sydney Olympics in 2000.

He also won world championship 100 titles in 1997, 1999 and 2001. At Seville, Spain, in ’99, he also won the 200 and 400-meter relay golds in a rare triple.

The following year, he won the 100 and anchored the victorious men’s 4×100 relay team at the Sydney Olympics, but did not run in the 200.

His world record of 9.79 seconds stood from 1999 until 2002, when Tim Montgomery ran a 9.78 – although that time was erased when Montgomery was banned for allegedly using performance-enhancing substances.

Asafa Powell of Jamaica set the record of 9.77 in 2005.

Greene still holds the indoor 60-meter world record at 6.39 seconds.

He acknowledged concerns among track and field athletes over the Chinese capital’s poor air quality, but said that shouldn’t be a barrier to victory at the Olympics.

“Every athlete who is coming here is going to be going for a gold medal. And they can’t let anything get in their way,” Greene said.

“Every athlete is going to have to deal with” air pollution, he said. “You’ve got to bust the door down and take what you want.”

Like many sprinters, Greene could be boastful like a boxer. At the start of a race, he’d attempt to intimidate opponents by flexing his muscles, staring them down or strutting impatiently up and down the running lanes hoping to distract rivals.

“I like to say I’m the GOAT,” he said. “The greatest of all time – in my time.”