DETROIT -- Tigers infielder Neifi Perez became the first player disciplined under Major League Baseball's testing program for banned stimulants Friday, receiving a 25-game suspension for a second positive test.

Stimulants were added to MLB's testing program last year in an effort to stop player use of such substances as amphetamines, or "greenies." A first positive test does not trigger a suspension and is kept anonymous, but the player can be tested up to six more times within the next 12 months without advance notice. A second positive test results in a 25-game suspension.

Surprisingly, Perez became the first example of the system at work. It wasn't known what substance triggered the positive result.

"I say to my fans that I am not stupid," Perez told the Dominican radio program Impacto Deportivo in his homeland, according to The Associated Press. "I know the difference between good and bad and there are things that are going to be known going forward, but my lawyer has advised me not to talk for now."

The suspension takes effect immediately. He would be eligible to return Aug. 4 against the White Sox during an 11-game homestand that includes Tampa Bay and Oakland.

Tigers players and officials discussed the news in a team meeting Friday afternoon, closing the clubhouse to media and visitors for about 35 minutes before batting practice. Afterwards, their comments generally focused responsibility on the player.

"Everybody is educated," Dombrowski said. "Everybody knows the program. It's presented by the Players Association and presented by Major League Baseball."

Said shortstop Carlos Guillen: "The rules are in the book."

Perez had been a useful reserve on a Tigers team that carries two utility infielders. Though he's batting just .172 (11-for-64) with a home run, three doubles and six RBIs in 33 games, his defense has been solid in spot starts filling in along the left side of the infield. He filled in for shortstop Carlos Guillen during a four-game series at Cleveland a month ago, and he made a skilled stop up the middle to start a critical inning-ending double play to preserve Justin Verlander's no-hitter June 12.

Manager Jim Leyland declined comment on the suspension, but he characterized the loss of Perez as something that will force them to adjust.

"I'd be stretching it if I said it was major," Leyland said, "but I think it's important to us, because he's such a good defensive player and can play anywhere. So it is significant."

To take Perez's place on the 25-man roster, the Tigers purchased the contract of outfielder Ryan Raburn from Triple-A Toledo. The recently announced Triple-A All-Star is batting .292 in 85 games for the Mud Hens with 17 home runs, 21 doubles and 64 RBIs. He also has drawn 51 walks, helping him to a .394 on-base percentage, and stolen 12 bases in 16 attempts.

Raburn, 26, made an impression on the parent club during Spring Training, when he hit .400 with three doubles, a home run and seven RBIs in limited playing time as a non-roster invitee. The Tigers sent him down late in camp with the idea of working him out in the outfield. Through Thursday, the converted infielder had made 45 starts in center field, 39 in left. He has not started in the infield this season, but he has taken ground balls at second and third base throughout the season and could be available there on a spot basis.