Manager Rick Renteria downplayed Rizzo's injury after the game.
"We don't think it's a serious issue," Cubs president Theo Epstein said Wednesday. "He's a big man, plays a lot of games. He's pretty flexible and achrobatic when he plays the field. The way he tweaked it [Tuesday] night with a day game [Thursday] following a night game tonight, [manager] Ricky [Renteria] thought it made sense to give him the day off."
Rizzo, 25, hit his 30th home run of the season in the victory against the Cincinnati Reds but left the game after grounding out in the seventh inning. He was seen laboring to first base after swinging and then was replaced in the next inning by Chris Valaika. Valaika will start at first on Wednesday.
Also in Wednesday's lineup is Cuban outfielder Jorge Soler, who will bat fifth. Soler, 22, will make his major league debut playing right field after compiling a .340 batting average and .432 on-base percentage to go along with 15 home runs and 57 RBIs combined at Double-A and Triple-A this season.
Soler signed a 9-year, $30 million deal in 2012 after defecting from Cuba.
The Cubs also recalled infielder/outfielder Logan Watkins on Wednesday. To make room for the additions, the Cubs placed outfielders Justin Ruggiano (ankle) and Ryan Sweeney (hamstring) on the disabled list.