Alvarez was struck in the groin area by a 105.3-mph liner off the bat of Blue Jays outfielder Lourdes Gurriel Jr. Alvarez managed to finish the play to record the final out of the fifth inning, then dropped to the ground and was taken off the field by a cart.
Tommy Hunter replaced Alvarez in the next inning. The Blue Jays earned a 3-2 win in the first game of the doubleheader on a walk-off single by Gurriel. Toronto also won the second game 9-8.
Alvarez, 31, has been one of the bright spots in the Phillies' struggling bullpen with a 1.42 ERA in eight appearances this season. Philadelphia's bullpen entered the afternoon with an 8.11 ERA, the worst mark in MLB.
Alvarez has a 3.60 ERA and 303 strikeouts in 358 career appearances with the Detroit Tigers, Los Angeles Angeles and Phillies.