Alvarez replaces Zimmermann in All-Star GameMarlins' first-time All-Star participant added to National League's roster
Zimmermann left Friday night's start against Philadelphia after 3 1-3 innings because of a right biceps injury.
Alvarez, a first-time All-Star, is 6-4 with a 2.63 ERA and three shutouts in19 starts. He pitched a no-hitter against Detroit on the final day of the 2013 regular season.
The roster change was announced Saturday.