Yamamoto (forearm) is scheduled to make an outing in the instructional league Monday and could rejoin the Marlins as early as next weekend, Andre Fernandez of The Athletic reports.
Yamamoto was given a slight chance to return this season just last week, but his prospects appear to have improved significantly over the last few days. Manager Don Mattingly indicated the young right-hander may not be used as a traditional starter upon his return in an effort to limit his innings with the season in its closing stages.