Minneapolis ? Minnesota Twins pitcher Juan Rincon, who emerged last season as one of baseball’s top setup men, became the highest-profile violator of major league baseball’s new policy on performance-enhancing drugs.

Rincon was suspended Monday for 10 days after testing positive for an undisclosed substance, the fifth player to be suspended this season.

Michael Weiner, general counsel of the Major League Baseball Players Assn., said a grievance would be filed today. But unlike other penalties, such as for fighting, suspensions under this policy take effect immediately and are not delayed pending a hearing.

“Suffice it to say, he was devastated and stunned by the result,” Rincon’s agent, Ed Setlik, said after speaking with Rincon, who is 2-1 with a 2.25 earned-run average in 12 appearances this season.

Last week, commissioner Bud Selig proposed much tougher penalties for players caught using steroids. He sent a letter to the union calling for a 50-game suspension for first-time steroid offenders, a 100-game penalty for a second offense and a lifetime ban for a third violation under what he called a “three strikes and you are out approach” to doping. Union head Donald Fehr sent a letter to Selig on Monday saying the players’ association was willing to discuss it.