Alex Rodriguez, baseball's highest-paid player and one of the sport's greatest hitters, has been suspended for a record 211 games for alleged doping offences.
Another 12 players, including three All-Stars, have been handed 50-game suspensions by Major League Baseball following a long investigation into links between top players and a Florida clinic accused of supplying performance enhancing drugs.
The 12 were all treated as first-time offenders and will serve their penalties - about eight weeks - in time to rejoin their teams for the postseason playoffs.
MLB commissioner Bud Selig says Rodriguez has been banned until the end of the 2014 season - the longest doping penalty ever handed by MLB - because he had committed other offences.
Rodriguez had previously indicated he would appeal to an arbitrator, allowing him to play until the case is resolved.
He is listed to play for the New York Yankees in Chicago today against the White Sox.
Although Rodriguez has never been punished for doping, he has previously admitted to doping, but said he stopped using steroids about a decade ago.
The 38-year-old is currently fifth on the all-time home runs list with 647 home runs but the ban threatens to ruin his prospects of overtaking Barry Bonds (762) as the all-time leader.