Cubs manager Mike Quade said Soto would have an MRI on Wednesday morning.
After Soto's injury, Triple-A Iowa catcher Welington Castillo was taken out of the game early in their game at Colorado Springs on Tuesday. Castillo will be in Chicago on Wednesday in case Soto has to go on the disabled list.
In the top of the first, Soto awkwardly blocked a pitch in the dirt thrown by Carlos Zambrano. Backup catcher Koyie Hill pinch hit for Soto in the bottom of the first.
Soto, the No. 8 batter in Chicago's order, is hitting .226 with three homers and 12 RBIs.
Bruce Levine covers the Cubs for ESPNChicago.com and ESPN 1000. Information from The Associated Press was used in this report.