"It went well," Richard said. "I took it like a game day -- got here early and went about it like I was preparing for a start."
San Diego manager Bud Black was encouraged as well, so much so that the team decided to send Richard on a Minor League rehabilitation assignment Thursday, when he will start for Triple-A Tucson on the road in Des Moines, Iowa.
"Going into the sim game, after two side sessions with [pitching coach Darren Balsley], the goal was to get his arm slot a little higher," Black said. "To get him back up on top of the ball, to get a better angle. Today, he repeated the arm slot, and the ball had good action."
As for the intestinal virus, Richard had a colonoscopy in San Diego on Friday and rejoined the Padres prior to Saturday's game against the Rays.
"I feel good," Richard said, adding that the doctors had "an idea what it might be. It's nothing serious, but it's something I might have to deal with in the future. The flu set off possibly something else."
Richard was slowed by a nasty virus for more than two weeks. He was 0-3 with a 13.09 in three starts while he tried to fight off the virus, which caused him to lose 12 pounds. Overall, Richard is 0-4 with an 8.54 ERA in six starts.
"I'm getting there," Richard said. "It was so long of up-and-down feeling. But I'm getting closer to my normal [in-season] weight ."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.