CHICAGO -- Cubs first baseman Anthony Rizzo did not start for a sixth consecutive day because of lower back tightness and may undergo an MRI to determine the extent of the problem.
Rizzo came out of last Tuesday's game in Cincinnati after his back tightened during a 50-minute rain delay. He has not started any of the Cubs' next seven games, including either game of a doubleheader on Saturday in St. Louis.
"He's still day to day, he's still a little stiff," Cubs manager Rick Renteria said Monday. "If it doesn't clear up, maybe we'll get an MRI to make sure everything's OK.
"He's doing fine," Renteria said. "We're just limiting him to make sure once he gets back on the field he doesn't have a setback."
Rizzo, who leads the Cubs with 30 home runs and 71 RBIs, was not available to pinch-hit Monday, Renteria said.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.