The team's prized prospect will undergo an MRI on his left elbow, Sox pitching coach Don Cooper told ESPN Baseball Insider Jim Bowden on his radio show Wednesday.
Sale had posted a 3-1 record and a 2.81 ERA this season before his abrupt shift to the closer's role on Friday. It had been reported then that elbow tenderness led to the move.
His first relief appearance came Tuesday, when he blew the save in a 5-3 win over the Cleveland Indians. A source familiar with the situation told ESPNChicago.com that an MRI had been scheduled before that outing.