Perez has been diagnosed with a Grade 1 plus left hamstring strain, Jaylon T. Thompson of The Kansas City Star reports.
Perez had to depart Sunday's game versus the Rays with the injury and is not in Monday's lineup against the Tigers. It sounds like the Royals are optimistic he can avoid a stint on the injured list, though, with a return in the next few days possible. Freddy Fermin is catching Monday.