"I'll reserve my optimism," Renteria said. "Today is the first day where he's gone out there. He's trying to see how his body is feeling, but I'll just say we'll keep digging it as it comes."
Rizzo has been listed as being out indefinitely after an MRI on Sept. 2 revealed a lower back strain. Renteria said he wants the injury to heal fully before Rizzo's return to the lineup.
"He's one to try and push himself to get back on," Renteria said. "And we all have to be mindful that we're looking to long-term benefits of having him as a position player for us. We're going slow and kind of making sure that if he does happen to get back that he's good to go."
• Renteria said Travis Wood's next start "might" be pushed back a day in favor of going with Jacob Turner. Wood, who'd normally be slated to start Sunday against the Pirates, is coming off a difficult outing against Pittsburgh in which he lasted only 1 2/3 innings and allowed nine hits and seven earned runs.
"We might make an adjustment," Renteria said.
Wood (8-12) has struggled at times this season, and is 1-4 with a 5.54 ERA in his last 10 outings.
Jamie Ross is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.