"It's just unfortunate," Braves manager Bobby Cox said. "I don't know. I don't know how to explain it."
After spending most of the previous five days taking batting practice, fielding grounders and testing the ankle with various running motions, Renteria was fully confident that the ankle injury that had sidelined him since Aug. 3 wouldn't be a problem.
Renteria's optimism was crushed when he left most of his weight on the right ankle while checking his swing and slightly moving back from Arroyo's first-pitch fastball. This was one motion he didn't simulate during the variety of tests that were performed.
"It's weird," Cox said. "He's been hitting for a week. Then he makes one crazy move that wasn't even startling to anyone and it grabbed him big time."
With the treatment he's received since exiting the game, Renteria has realized immediate relief. He isn't walking with much of a limp and isn't feeling any discomfort when Braves head athletic trainer Jeff Porter twists and turns the ankle in many directions.
"[Porter] can't do one thing to make it hurt one bit, even after he came out of the game last night," Cox said. "He can put him in every position he can put him in and it doesn't hurt one bit. ... But there's something wrong, obviously."
The Braves have instructed Renteria to not do any baseball activities over the next week. He's permitted to ride a stationary bike to keep his legs in shape.
Without any sense of troublesome discomfort present, Renteria doesn't believe Wednesday's setback put him back where he was when he originally sprained the ankle on Aug. 2. With this in mind, he's hopeful that he'll be ready when he's eligible for activation on Sept. 7.
"It's difficult [since] we are right there in the race," Renteria said. "That's why I tried to play. Hopefully we can keep it close, so that when I come back, I can help."
Dotel's test comes Friday: There was no reason to believe Octavio Dotel was going to come off the disabled list when he became eligible for activation on Thursday. But when he throws a bullpen session in St. Louis on Friday, the Braves will gain a better sense of when the right-hander might rejoin their bullpen on Friday.
Dotel, who was placed on the disabled list on Aug. 10, was encouraged Wednesday after feeling no discomfort while playing catch at a distance of about 120 feet.
Rotation worries: With Philadelphia placing Cole Hamels on the 15-day disabled list and San Diego wondering how long Chris Young's ailing back will keep him sidelined, there's definitely reason for Atlanta to feel better about its chances of winning the National League Wild Card.
Entering Thursday's series finale against the Reds, the Braves trailed the front-running Padres by two games and the Phillies by 1 1/2 games.
But sticking with the belief that you can only worry about your own team, there's obviously reason for the Braves to worry about the damaging effects the back end of their rotation might create.
Over the course of the past 14 games, Braves starting pitchers have gone 4-5 with a 5.63 ERA. Tim Hudson has accounted for three of those wins and John Smoltz the other. In the games these two haven't started during that span, the other Atlanta starters have posted a 7.34 ERA.
Prado stays: To make room for Renteria on the 25-man roster on Wednesday, the Braves optioned Martin Prado back to Triple-A Richmond. But truth be told, Prado never even exited Great American Ball Park.
When Renteria proved healthy during batting practice, Prado began packing his belongings. When Renteria aggravated the ankle injury, the infielder began unpacking.
With Renteria now back on the disabled list, Prado was recalled from Richmond and will now be with Atlanta through the end of the regular season.
Coming up: The Braves will open a three-game series against the Cardinals on Friday night at 8:10 p.m. ET. They'll send Smoltz (11-6, 3.05) to the mound to oppose Kip Wells (6-13, 5.24).