Out since an appendectomy on July 9, Vargas has missed three starts with fellow lefty Bruce Chen taking his spot.
"Every day that I threw, there were big progressions as far as how I felt each time," Vargas said.
On Saturday, there was no pulling sensation where the appendix was removed.
"I think I got over that hurdle the last time I got off the mound, and [Saturday], I was just pretty much focused on executing pitches and it went all right," Vargas said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.