All Houston's runs came on solo homers, which gave the Astros a 5-4 lead through five innings.
Drew Stubbs then singled home Wladimir Balentien with the tying run in the sixth and the Reds took the lead in the seventh, thanks to a gift from Jeff Fulchino.
Votto led off the seventh with a single and moved to third on a base hit by Brandon Phillips.
Fulchino then came in to relieve Wesley Wright and promptly uncorked the wild pitch that brought home what turned out to be the winning run.
Jared Burton (1-0) got the victory as the third of five Cincinnati pitchers. He retired all five men he faced. Francisco Cordero worked a perfect ninth for his 37th save. Wright (3-3) took the loss.
Jeff Keppinger hit two of Houston's home runs. The other blasts came from Kazuo Matsui, Carlos Lee and Geoff Blum. All five homers came off starter Justin Lehr.
Copyright 2009 by United Press International.