Despite a hard, somewhat-acrobatic fall, Rizzo escaped with just a bruised right shoulder. Manager Dale Sveum said Rizzo was available to pinch-hit in Wednesday's series finale.
"He's just sore on the right side," Sveum said. "Everything else checks out good. No head problems. No leg problems. Just a little bit sore on his upper right side. He took some swings in the cage and he was OK."
Sveum said he thought Rizzo was going to be seriously injured after watching the first baseman's 6-foot-3, 220-pound frame hit the ground.
"Even watching the replay, there's a lot of things flying around," Sveum said. "A big body hitting the ground pretty hard. I think we're very fortunate that we got away with that one."
Anthony Recker, normally a catcher, manned first base and batted eighth Wednesday night. He hadn't played first base in the Majors, but logged 27 games at first base in the Minors, 26 of them with Triple-A Sacramento, the A's affiliate.
"He's played there enough," Sveum said. "He'll give us a right-handed bat in the lineup and we'll see what happens."
Sveum decided not to play first baseman Bryan LaHair, who is batting .063 (3-for-48) against left-handed pitching this season. Left-hander Fernando Abad started for the Astros on Wednesday.