Manuel played the entire first half of the Bills' 44-20 win over the Indianapolis Colts yesterday, successfully completing 16 of his 21 passes and also throwing a touchdown.
The 23-year-old took his side on a 95-yard drive in the closing stages of the half, completing nine of nine passes including a 17-yard touchdown pass to tight end Dorin Dickerson, a move that Marrone was particularly happy with.
"Here you are right before a half, 1:50, three timeouts left, and you're making decisions. Are we going to try to run out the clock? Are we going to go 2-minute? Hey, let's go 2-minute," said Marrone.
"To do that is very impressive, no matter who you are."
Manuel is currently competing with veteran quarterback Kevin Kolb for the starting jersey ahead of the new NFL season.