Yamamoto (shoulder) had his rehab assignment transferred to Triple-A Syracuse on Saturday, Anthony DiComo of MLB.com reports.
Yamamoto allowed one run on three hits and no walks while striking out five in four innings at Low-A St. Lucie last week, and he'll now progress to the top level of the minors. The Mets haven't yet announced when the right-hander will be able to return, but he'll likely be in the mix to be activated sometime next week.