Reds manager Dusty Baker initially had Phillips in the lineup Saturday, but he made a late scratch and started Wilson Valdez in his place.
"It was a tough decision, with much deliberation from our medical staff and Brandon and Walt [Jocketty, general manager]. We did the best thing for him," Baker said. "We're trying to get him back where he doesn't have to come out on defense, or we don't have to pinch-run for him so he doesn't take a chance on pulling that calf."
Phillips was out of the lineup again Sunday, and while Baker said he couldn't pinpoint an exact return date for his Gold Glove second baseman, he did call Phillips "real, real, real close."
"It's not very pleasant telling him he's not in the lineup, because he loves to play," Baker said. "I'm a manager, not a doctor. Through much discussion, we decided it would be better medically because of the potential repercussions if he did hurt it seriously and how long he could be out."
Entering Sunday, Phillips was batting .296 with 13 home runs and 62 RBIs this season and has been an instrumental part of the Reds' offense in the absence of Joey Votto, hitting .339 with three homers and 13 RBIs since Votto left the lineup.
Baker said Phillips likely would be available to pinch-hit in a two-out, non-double-play situation late in the game, if needed.