Manager Bobby Cox said the shortstop felt some lingering pain in his sprained right ankle during a running drill Friday and needs more time to recover.
"He did some figure eight running, and it just got him a little bit," Cox said. "He's not going to be ready in the next couple days, for sure."
Renteria has been out since Aug. 3 with a high ankle sprain that put him on crutches at first. He doesn't appear to have had any trouble walking this week and has been doing limited exercises at Turner Field.
Saturday was the first day Renteria was eligible to return, but Cox indicated the injury could keep him out until next weekend's series at St. Louis.
"I don't know for sure," he said. "He hasn't hit outside yet, and he hasn't taken ground balls."
The Braves have missed Renteria's bat in the No. 2 spot. Before the injury, he was hitting .336, which would be a career high if he kept it up through the end of September.
COOLER PRACTICE: Cox gave his players a break from the heat Saturday, canceling outdoor batting practice and allowing them to arrive at Turner Field as late as 5:30 p.m. - about 90 minutes before game time.
"We gave them a day off from working and just let them play the game," Cox said. "I probably should do it three or four days in a row, to be honest. They'd be better off."
The Braves played in scorching, humid weather last week in New York and returned home in the midst of a record heat wave in Atlanta. Friday was the eighth day this month in which temperatures reached 100 degrees or higher - a city record, according to The Associated Press.
MILLER STARTS: Corky Miller started at catcher Saturday as Cox looked to give Brian McCann a night off. It was only the second start for Miller since he replaced Jarrod Saltalamacchia as Atlanta's backup catcher.
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