SAN DIEGO -- After deliberation, the Mets placed reliever Tim Byrdak on the disabled list before Friday's series opener with shoulder discomfort to clear the roster spot for Frank Francisco.

Byrdak said he injured himself delivering a slider in the road trip opener in Arizona last Thursday. He will have an MRI on Monday in New York to determine the extent of the injury.

"I threw that last slider on a strikeout and I just kind of felt something in the back of my shoulder roll a little bit," Byrdak said. "I started seeking treatment on it right away, but it was a situation where it's still there. It's not getting any better. Knowing the roster move [with Francisco], I didn't want to leave Terry [Collins] a man short. We thought the best position to take was to go ahead and go on the DL and give it some time to calm down."