The New York Yankees baseball slugger Alex Rodriguez allegedly tested positive for two anabolic steroids in 2003.
Sports Illustrated, which quotes four independent sources, says Rodriguez's name was on a list of 104 players who tested positive for performance-enhancing drugs in Major League Baseball's 2003 survey testing.
Rodriguez, who has a chance to become the game's all-time home run champion, won the American League Most Valuable Player award as a shortstop for the Texas Rangers that year.
Rodriguez has declined to comment.
While major league baseball's drug policy has banned the use of steroids without a valid prescription since 1991, there were no penalties for a positive test in 2003.
That year's survey testing was conducted as part of an agreement with the players' union to determine if it was necessary to impose mandatory random drug-testing across the major leagues in 2004.
The results were meant to remain anonymous.
New York signed Rodriguez in November 2007 to a 10-year, incentive-laden deal that could be worth as much as US$305 million, according to Sports Illustrated.