Jimenez, who has 105 wins, took the responsibility to heart.
"It's not easy, not facing hitters for a few days and then coming in," Jimenez said. "You have to find a way to be ready. I can help take the pressure off the main guy."
Jimenez has made 18 starts, and Sunday was his second relief appearance.
• Outfielder Steve Pearce, who received a cortisone shot for an inflamed right elbow, "looks a lot better than initially," Showalter said. "By Wednesday, we'll have an idea what we're dealing with."
• Lefty T.J. McFarland will throw a bullpen session for the Orioles' Rookie League affiliate in the Gulf Coast League on Tuesday. If all goes well, he'll be sent on a rehab assignment.
Rick Eymer is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.