Guerra pitched two-thirds of an inning against Arizona on Monday and gave up four runs on five hits while striking out one.
Guerra had previously spent time in the majors as a hitter but was making his big-league debut as a pitcher after switching positions at the start of the season. He came on in the sixth inning and struck out the first batter he faced but then gave up a long home run to Josh Rojas. After retiring Ketel Marte, the next two batters also went deep, and Guerra was pulled after giving up another pair of hits. Despite the rough outing, the 23-year-old should get additional opportunities after showing well in the minors this season.