Nova left Saturday night's game against Tampa Bay in the fifth inning. An MRI exam after the game revealed the injury and he was put on the 15-day disabled list.
Nova will be further examined Monday in New York by Yankees team physician Chris Ahmad. He had no discomfort in the elbow until his 82nd and final pitch Saturday, when he felt a pop.
If Nova needs elbow-ligament replacement surgery he could be sidelined more than a year.
Schafer strained his right hamstring while stretching in the on-deck circle prior to a pinch-hitting appearance Thursday against the Pirates. The move was made retroactive to April 18.
Overbay and wife Sarah welcomed their fifth son, Eddie Christian Overbay, on Thursday.