Downs' tiebreaking, pinch-hit, two-run homer capped a four-run outburst in the ninth off the Texas Rangers closer and gave the Astros a 5-3 victory Wednesday night to avoid being swept in the first half of the Lone Star Series.
"There's no doubt it's a confidence booster, just with the guys battling so much," Astros manager Brad Mills said. "They were able to get something for it. ... That was sweet."
The Astros (28-48) still have the worst record in the majors. But their 10th victory in their final at-bat gave them a split of their six-game trip before heading home for nine interleague games.
Houston had four hits off Feliz (0-1), who had a 35-pitch save Tuesday night against the Astros.
"I'm sure his arm wasn't as live as it would've been on a fresh night," Downs said. "We were actually surprised to see him in there. We figured we would see somebody else. Thank goodness we did."
The Astros trailed 3-1 when Carlos Lee greeted Feliz with a bouncer just over third base that rolled into the left-field corner for a double. Lee came home on a double by Chris Johnson before an infield single by Jason Michaels. Johnson scored on a passed ball before Downs' fourth homer of the season and the quick trot.
"I probably had a little adrenaline going at that time," Downs said. "It probably kicked in, a little excited."
Before that, the Astros hadn't homered in eight games, their longest such streak since August 1992.
Downs has reached safely in nine of his past 12 pinch-hit appearances (four hits, four walks and a hit by pitch). When Mills decided to bat for shortstop Clint Barmes, a .215 hitter, the manager knew who was going to the plate.
"He's done a real good job off the bench, swinging the bat for us. That was a key spot for him," Mills said. "He's been hitting the ball out of the ballpark, but we just felt real confident with him putting a good swing on the ball, wherever it went."
That made a winner of reliever Mark Melancon (5-1), who pitched a perfect ninth after being given a lead. The right-hander had walked the first two batters he faced when he took over to start the eighth before Michael Young's RBI double gave Texas a 3-1 lead.
The meltdown by Feliz wasted an impressive outing by Rangers starter Colby Lewis, who dealt with neck spasms while throwing seven scoreless innings.
"We had a 3-1 lead, the closer was in there, we just didn't get it done," manager Ron Washington said. "You have to tip your hat to the Astros. They swung the bat there in that ninth inning."
Before Wednesday's game, Washington had called Feliz's 35 pitches the previous night "effortless" and said the closer was available for the finale before a day off Thursday.
"I felt good but I just didn't have the good result," Feliz said. "My arm was OK. I didn't feel anything that wouldn't let me come in today."
The teams open another three-game series Tuesday night in Houston. The AL West-leading Rangers will try to claim the Silver Boot Trophy for the fifth season in a row.
Nelson Cruz had a long homer for the Rangers, putting them up 2-0 when he led off the fifth with a 415-foot homer to left field. His 17th homer of the season ricocheted off the facade of a club located above the first 15 rows of seats.
That was the 20th homer this season allowed by Brett Myers, who came into the game tied with Lewis for the most homers allowed this season. The Rangers got their first run on a wild pitch by Myers, who struck out six while allowing two runs over six innings.
Dave Bush benefited from a double-play grounder that got out Houston's two fastest runners after taking over for Lewis, who allowed only three hits and struck out eight.
Bush gave up singles to pinch-hitter Angel Sanchez and leadoff hitter Michael Bourn to start the eighth. Sanchez scored when Jason Bourgeois hit into a double play that also got out Bourn. Bourgeois and Bourn have 49 stolen bases between them.
Ian Kinsler led off the Texas first with a single and a stolen base. He went to third on a groundout and scored on a wild pitch while Adrian Beltre was at the plate before striking out to end the inning.
Sanchez pinch-hit for C Carlos Corporan, who was replaced in the field in the eighth by J.R. Towles, who had missed seven consecutive games because of leg soreness. ... Astros 1B Brett Wallace is in an 0-for-20 slide after going 0-for-3 with a walk. ... Both teams have Thursday and Monday off. The Rangers are home this weekend against the New York Mets. The Astros host Tampa Bay.