Manager Bryan Price said on Friday it's unclear when Cueto will rejoin the club. He's scheduled to pitch the season opener in Cincinnati on April 6 against Pittsburgh.
Cueto was scheduled to start on Friday against the Giants in Scottsdale. Anthony DeSclafani took his place. Price said Cueto is fine physically and will continue throwing in the Dominican Republic.
The 20-game winner is entering the final year on his contract. He's been hoping to have a new deal before opening day.
The Reds already had concerns about their rotation. Homer Bailey is recovering from forearm surgery, and two other spots were opened by offseason trades.