Former five-time world sprint champion and former world record-holder Maurice Greene announced his retirement from track and field today following a spat of injuries which have derailed him for the past two seasons.

Greene, who twice set the world indoor 60m record (6.39) and holds the American 50m record (5.56) indoors, set the American 100m record (9.79) in Athens nine years ago.

Greene's 100m time still ranks among the top-5 on the world all-time list. Jamaican Asafa Powell (9.74) holds the current world-record.

Greene won a bronze medal at the 2004 Olympic Games in Athens along with a gold (100m) and bronze (4x100m) at the Sydney Olympics in 2000, but is best known for his 2001 100m victory at the IAAF World Outdoor Championships in Edmonton, where he ran a 9.82 after injuring himself halfway during the race - one he won over fellow American, Tim Montgomery.

Montgomery would later lower Greene's world record to 9.78 seconds, but would be stripped of that honour following revelation that he had received and used performance-enhancing drugs from BALCO laboratories.

Greene, who was coached and trained by John Smith's HSI track club at UCLA, ran an incredible 52 races under the 10.00-second flat barrier — one of the marks a by which world-class sprinters are gauged to have been successful in their careers. Greene broke 10.00-flat every season between 1997 and 2004.

Greene also held a 19.86 best over 200m.

Tattooed on Greene's shoulder are the letters GOAT, an acronym for Greatest of All Time. Greene considered himself better than Jesse Owens, the American Olympian who won four gold medals at the 1936 Games in Berlin and Carl Lewis, the American who equalled that feat 48 years later at the Los Angeles Olympics.

Powell has since taken the world record from Greene and lowered it 0,05 seconds in becoming the World's Quickest Man.  The World's Fastest Man, a title which is awarded the Olympic 100m champion, is Justin Gatlin, an American sprinter who once co-held the world record with Powell, but is now staving off drug allegations as he awaits a hearing with the Court of Arbitration for Sport in New York.

Yet another American, Tyson Gay, is the current man to beat as the Beijing Olympics loom, having defeated Powell at last summer's IAAF World Outoor Championships.  Gay has run 9.84 seconds over 100m - a time which equals the fourth best performers in history, and has the second-fastest 200m runner in world history (19,62) behind Michael Johnson's world-record time of 19.32 set at the 1996 Olympics in Atlanta. 

Greene, who hails from Kansas City, finished his career 1-2 against Asafa Powell and 2-0 over Gay - though Gay won the adidas Classic in Carson, CA last summer in 9.79 - a final to which Greene failed to qualify.