WASHINGTON -- The Nationals have decided that right-hander Tyler Clippard will pitch against the Mariners on Saturday night instead of left-hander Odalis Perez.

Clippard last pitched for the Nationals on Monday night against the Giants at Nationals Park. Clippard lasted 4 1/3 innings, giving up three runs on five hits. His only clean inning occurred in the third. Clippard ended up throwing 98 pitches in the game, while struggling with the command of his fastball. Clippard was optioned back to Triple-A Columbus after the game.

Perez has not pitched since June 3, because of shoulder tendinitis, and there is a possibility he could be placed on the disabled list. He has already missed a start because of the injury.