Mejia was recalled from Triple-A Rochester on Saturday, the Star Tribune's LaVelle Neal reports.
Saturday was the southpaw's day to start at Triple-A, but he will apparently work out of the bullpen to start his big league career. Mejia, who the Twins acquired from San Francisco for Eduardo Nunez at the trade deadline, is one of the team's best pitching prospects, with the potential to be a No. 3 starter down the road. He could be pretty overpowering out of the bullpen in short bursts over the rest of the season, especially against lefties. He has thrown 125 innings this season after logging just 82.1 innings last year between the minors and the Arizona Fall League, so it is not surprising that the Twins are looking to manage his innings down the stretch.