OAKLAND, Calif. (AP) - Oakland Athletics pitcher Frankie Montas has been suspended 80 games by Major League Baseball after testing positive for a performance-enhancing substance.

The penalty was announced Friday, a day after another fine outing by the 26-year-old right-hander. He is 9-2 with a 2.70 ERA in 13 starts.

The A's are 40-36, meaning Montas could return for the final week of the regular season. Montas, however, becomes ineligible for postseason play this year.

The commissioner's office said Montas tested positive for Ostarine, a PED. He is the sixth player this year suspended under the major league drug program.

In a statement released by the players' union, Montas said he never intended to use a banned substance. He said he unknowingly took a contaminated supplement that he bought over the counter at a nutrition store in the United States.