Riley (knee) began a rehab assignment Thursday and went 1-for-3 with a strikeout for the rookie-level GCL Braves, David O'Brien of The Atlanta Journal-Constitution reports.
Riley landed on the disabled list in early June with a right knee sprain and Thursday marked his return to action. The 21-year-old will likely remain with the GCL Braves for a few games to re-acclimate himself before returning to Triple-A Gwinnett, where he slashed .284/.345/.431 with 38 strikeouts in 102 at-bats this season.