Strasburg suffered a strained flexor mass on Sept. 7.
Manager Dusty Baker said pitcher is "game ready."
The mid-season acquisition was chosen to start over Lucas Giolito and Reynaldo Lopez.
Ross threw 60 to 65 pitches to teammates at Nationals Park Saturday afternoon.
Joe Ross might be back soon, but that does not solve everything for these Nationals.
After Wednesday night at Nationals Park, what looked like a formidable 1-2-3 pitching punch for the postseason is now racked with uncertainty.
Max Scherzer will pitch on an extra day of rest, while Stephen Strasburg could return Wednesday to close the series.
In other rotation news, both Mike Rizzo and Mike Maddux expect Stephen Strasburg to come off the disabled list when ready.
The right-hander got called up from Syracuse Friday, and said he is nervous and excited for the opportunity.
The Nationals will skip a fifth starter thanks to Thursday's off day.