The late rally left second-place Cincinnati two games behind idle St. Louis in the NL Central. The Reds have stayed in contention by beating their division rivals, going 37-29 overall and 8-2 against the fading Astros.
Aubrey Huff hit two home runs for Houston, which has lost eight of 10.
Huff had a pair of solo homers, Lance Berkman connected off Bronson Arroyo and Willy Taveras extended his hitting streak to 24 games with a bunt single as Houston pulled ahead 3-0 after seven innings.
Then, Houston's balky bullpen let it slip away.
Chad Qualls (4-3) gave up a pair of hits and a first-pitch homer by Aurilia, who also had a pair of infield singles and a double. After two more singles, Clayton singled up the middle with two outs to give the Reds their first lead.
Ryan Franklin (4-6) pitched a perfect eighth to get the win, and newcomer Scott Schoeneweis got the last three outs for his first save. The Reds are using a collection of relievers to close games while Eddie Guardado is on the disabled list with a sore forearm.
The no-decision left Arroyo stuck in a two-month slump. The All-Star has only one victory in his last 12 starts, the result of misfortune and mistakes that prompted him to briefly change his hairstyle for luck.
Again Monday, there was no such luck. He gave up only five hits, including solo homers by Berkman and Huff, but left trailing 2-0 after six innings.
All that did was set up another late Reds comeback.
Andy Pettitte matched his season high by fanning 10 batters in 5 1-3 scoreless innings, leaving after his 118th pitch. He allowed six hits and escaped bases-loaded threats in the second and third innings, then turned a 2-0 lead over to the bullpen.