A first-time All-Star, Manoah entered 11-4 with a 2.24 ERA in 19 starts.
Schoop's one-hopper deflected off Manoah to shortstop Santiago Espinal, who made the out at first as Manoah walked off the back of the mound, grimacing in pain.
Following a conversation with an athletic trainer, a frustrated Manoah walked off the field. He was replaced by left-hander Tim Mayza.
Manoah allowed four runs and seven hits in 5 1/3 innings. He walked one and struck out four.
Manoah went 9-2 with a 3.22 ERA in 20 starts as a rookie last season.