The alarm, however, was unnecessary: The Pirates' plan to ease Walker back into full-time, healthy service had included the scheduled break.
"I feel as good as I did [Friday night]. We just want to ensure everything stays quiet [with the back]," Walker said.
Walker is due to play each of the next three games. He may next sit out Wednesday night's start at home, to give him two more rest days with Thursday's off-day in the schedule.
"We've mapped out a plan for us to maximize his availability," manager Clint Hurdle said. "Our goal is to keep him on the field the rest of the season."
The Bucs thus began Saturday's game with their regular double-play tandem on the bench. Shortstop Jordy Mercer continued to get a variety of treatments for right forearm tightness. Mercer reported feeling better, ruling out the possibility of having to go on the disabled list.
"We're confident he'll be able to return well before 15 days," said Hurdle, citing the minimum term on the DL. "Meanwhile, we'll try to limit his activities."
Jayson Nix started at second against Washington lefty Gio Gonzalez, and Josh Harrison stayed at short.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. This story was not subject to the approval of Major League Baseball or its clubs.