Gio Gonzalez was “a little stiff” and had his throwing session pushed back Friday. (Alex Brandon/Associated Press)

Nationals left-handed starter Gio Gonzalez planned to play catch Friday afternoon for the first time since an MRI last weekend revealed left shoulder inflammation. But he felt,  “a little stiff still,” Manager Matt Williams said, so Gonzalez stuck to his rehab and strengthening program for another day and will try to play catch again Saturday.

“It’s normal,” Williams said. “We set out the plan and try to go that plan. Sometimes, you got to make adjustments. It’s only a day. I think he’ll be good to go tomorrow. We just push him a day.”

Gonzalez will be eligible to come of the disabled list June 2, but the Nationals are not aiming for him to be ready by then. The Nationals are not yet certain how many starts Gonzalez will miss, but they do not expect him to miss significant action.

“It depends on him and how he feels, what he feels like when he gets to his bullpen,” Williams said. “It’s still kind of up in the air. We don’t know yet. The good thing is, he’s strengthening and continuing to treat it.”

Williams said Gonzalez may or may not pitch at a minor league affiliate on a rehab assignment. If they can arrange for him to pitch a simulated game once he’s ready, they would prefer that.

The Nationals have replaced Gonzalez with rookie Blake Treinen, who Thursday night allowed two runs in 5 2/3 innings, hitting 98 miles per hour with his sinking fastball. In 17 1/3 major league innings, Treinen has a 1.56 ERA.