Riley is out of the lineup for Monday's game against the Cubs and is slated to undergo an MRI on his injured left side, David O'Brien of The Athletic reports.
Riley was lifted in the bottom of the fourth inning of Sunday's 4-3 loss to the Mets after experiencing left side tightness, which reportedly first surfaced during batting practice earlier that day. While Atlanta remains hopeful that Riley isn't dealing with a long-term injury, more will be known once the MRI results are in later Monday. Zack Short will pick up a start at the hot corner Monday while Riley exits the starting nine for the first time all season.