Arizona Diamondbacks right-hander Merrill Kelly was scratched from his start Sunday against the host San Francisco Giants.
Manager Torey Lovullo said Kelly is experiencing shoulder discomfort and had an MRI on Saturday night. There was no immediate word on what those tests showed.
Kelly is 2-0 with a 2.19 ERA in four starts this season.
Right-hander Slade Cecconi will start the game and make his season debut after being recalled from Triple-A Reno earlier Sunday.
Cecconi, 24, posted a 2-2 record with a 4.58 ERA in four starts with Reno. He went 0-1 with a 4.33 ERA in seven games (four starts) last season with Arizona.
Also on Sunday, the Diamondbacks optioned right-hander Justin Martinez to Reno.
Martinez, 22, contributed three scoreless innings over two relief appearances this season.
Information from Field Level Media was used in this report.