Atlanta placed Riley on the 10-day injured list Saturday with a right abdominal strain.
Riley's abdomen forced him to make an early exit during the fourth inning of Friday's contest, and now that further evaluation has confirmed a strain, he'll remain on the sidelines until at least July 22. Nacho Alvarez will come up from Triple-A Gwinnett to replenish Atlanta's infield depth, though Luke Williams is the most likely option to take over at third base until Riley returns.