"I've got an idea about where we're going to go there, but I want to see how things go tonight," Showalter said.
Kevin Gausman or Bud Norris will be in line to take the mound for Sunday's series finale. Saturday would be Gausman's turn in the rotation, so his start will pushed back a day at least. Norris, meanwhile, would be pitching on regular rest should he get the ball.
Showalter wouldn't say if a bullpen stint was in store for one of his starters. A corresponding move on the 25-man roster won't have to be made until Jimenez is activated.
"We don't have to make a move for Ubaldo until Saturday," he said. "But if we have issues in our bullpen that we want to cover tomorrow, we'll make it before Saturday."
Jimenez threw a 35-pitch side session prior to Wednesday's loss to the Blue Jays and said that it was his "best bullpen of the whole year."
The right-hander has been on the 15-day disabled list with a sprained right ankle since July 13. Jimenez signed a four-year, $50 million contract with the O's in February.
The 30-year-old has struggled this season, posting a 3-8 record with a 4.52 ERA in 18 starts.
"He's healthy, he's ready to go, he's physically in good shape and looking forward to getting back in the fight and helping his teammates," Showalter said.