"It's just inflammation," Infante said. "It's happened to me before, last year. In a couple days, I think I'll be better. Maybe I'll be ready for Saturday."
So far, there's no disabled list for Infante and no callup of an infielder from the Minor Leagues.
"We're already looking at our options," manager Ned Yost said. "We don't think it's going to be a DL thing. We know with where he's at today, he's not going to be available [Friday].
"We'll just go from that point on. If he's not any better [Friday], we'll just shoot for Tuesday after the off-day and see if he's going to be OK by then."
Infante's back stiffened up after Tuesday night's game at San Diego and he tried to be ready for Wednesday afternoon's game.
"He felt good, he got it all loosened up. He went in and tried to take some swings and still felt it a little bit," Yost said. "But as the day went on, he stiffened up again."
"I felt pretty good," Infante said. "The only thing I couldn't do was take ground balls."
That's a definite drawback for a second baseman.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.