Rosenberg will be called up from Triple-A Salt Lake to start Sunday's game against the Mariners, Rhett Bollinger of MLB.com reports.
Rosenberg's first two major-league appearances came as a reliever, and he allowed five runs while striking out seven in six innings. He was sent to the minors in early June but will rejoin the big-league club to make his first career start in the majors Sunday. Over seven starts with Salt Lake this year, he's posted a 2.34 ERA and 0.96 WHIP in 34.2 innings.