Liberatore, who came over from Tampa Bay in the Joel Peralta trade and is vying with Paco Rodriguez to be the second lefty in the bullpen, struck out two in a perfect inning and drew praise from manager Don Mattingly.
"He's got great stuff," Mattingly said. "The ball comes out of his hand different. He has a nasty split, throws to both sides of the plate, and it comes out of his hand funny -- like a cannon."
Aardsma, a former closer determined to revive his career, struck out the side in the eighth inning.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.