Olympic hero or bookies' nightmare?

By Belinda Goldsmith

BEIJING (Reuters) - He's the hero of the Beijing Olympics -- but Michael Phelps has become the bane of bookmakers.

Gamblers have joined Phelps's winning streak with online betting sites reporting a spike in money riding on the U.S. swimmer and higher interest overall from gamblers in the Games.

Phelps has been the favourite in all of his races in the August 8-24 Games on various online betting sites, with odds for his victories down to about 5/2 on -- paying out about $40 on a $100 bet.

"Although he has been at short odds to win he has being doing the right thing by the punters who are getting back more than they get on bank interest," said Phil Hannah, general manager at Australia-based online betting site SportsBet.

"He really has become a thorn in the bookmakers' side."

Most gamblers are betting Phelps will beat compatriot Mark Spitz's record of winning seven gold medals at one Olympics, with the 23-year-old already snapping up five golds from Beijing, making him the most decorated Olympian of all time with 11 golds.

He is due to swim the 200 metre individual medley on Friday, the 100 metre butterfly on Saturday and the 4x100 metre medley relay on Sunday.

Online site Sky Bet is also paying 5/2 on for Phelps to beat Spitz's record.