Gio Gonzalez throws a sim game on Sunday. (AP Photo/Alex Brandon)

Blake Treinen threw 45 pitches as part of a simulated three innings while facing teammates a few hours before Tuesday’s game against Philadelphia, a way to keep him fresh before his next start on Saturday in San Diego.

Treinen hasn’t pitched since Friday and hasn’t started since May 22. The rookie right-hander hasn’t been needed in the starting rotation because of a rainout and two scheduled days off, as the rest of the club’s starters have been kept on close to regular rest.

That, however, could be the last start the Nationals need from Treinen with Gio Gonzalez nearing a return from shoulder inflammation that landed him on the disabled list. Gonzalez threw a bullpen session of about 50 pitches at Nationals Park on Tuesday, two days after throwing a simulated game.

Gonzalez’s next step would be to make a minor league rehab start with Class A Potomac on Friday, according to Nationals Manager Matt Williams. The Nationals expect Gonzalez to increase his pitch count to 65 and be ready to re-join the Nationals rotation after that if there are no issues.

“Even at 65, we’re still pushing him,” Williams said. “It’s fairly quick. He hasn’t gotten to a 100 yet. We’ll have to see.”

On that schedule, Gonzalez could start for the Nationals on June 11 in San Francisco.