Mejia was optioned to Triple-A Rochester on Sunday, Rhett Bollinger of MLB.com reports.
Mejia had been called up by the Twins on Saturday, but is already headed back down to Rochester. During his MLB debut, Mejia allowed two runs off five hits and a walk over the course of just 2.1 innings. Mejia's performance with rochester has also been underwhelming, as he's 1-2 with a 4.66 ERA after three starts.