Jason Lane hit a three-run homer in the eighth inning, completing a two-out rally that lifted the Astros to a 7-2 victory on Wednesday night.
Down 2-1, the Astros scored five times in the eighth against a bullpen that hadn't surrendered a lead so late.
"Our big dogs were coming up to the plate, so I knew we had a pretty good shot," starter Chris Sampson (2-0) said.
Not surprisingly, Lance Berkman was a big part of the Astros' comeback for their sixth victory in seven games. Berkman, who has had some of his biggest games against the Reds, singled home the tying run with two outs off Todd Coffey (1-1).
After pinch-hitter Mark Loretta gave Houston a 3-2 lead with a single off Rheal Cormier, Lane hit the left-hander's first pitch for his third homer, completing a comeback that relied heavily on players accustomed to coming off the bench.
"We've got a great bench," said Lane, who has started five games. "Hopefully it's going to help this team out a ton."
The rally started when Coffey hit Orlando Palmeiro, who was pinch-hitting for Sampson. Coffey has hit three batters in his past three appearances, playing a key role in a pair of losses.
He hit Sampson on the shoulder while trying to back him off the plate, and immediately started second-guessing himself.
"I'm just off the plate," said Coffey, who hit only two batters last season. "I'm trying to do stuff I don't normally do. Last year, I didn't try to go up and in so much. Maybe I should try to go back to what I did last year - throw more sinkers low and away."
It was a rousing start to an unusual trip for the Astros -- nine games in four cities. They play two in Cincinnati, three in Milwaukee, one in Philadelphia and three in Pittsburgh, a good early test for a team that was 38-43 on the road last season.
Until the late meltdown, the Reds were in position for another win behind Harang, who beat the Astros in all four of his starts last season and was ahead 2-1 when he left the game after the sixth.
The only difference this time was that Harang threw a lot of pitches -- 101 -- to cut his outing short. The right-hander threw 30 pitches in the fourth inning.
"When you're playing against a guy who has pitched well against you, the best thing you can try to do is get his pitch count up," manager Phil Garner said. "That turned out in our favor."
Harang struck out eight and allowed only three hits, but wished he could have gone longer.
"I'd rather have a hundred (pitches) in eight innings," he said. "I had to throw a lot of pitches in that one inning, and mentally and physically, it takes a lot out of you - more mentally."
Carlos Lee drove in the only run off Harang with a groundout in the sixth inning, the outfielder's 17th RBI in 13 games. Lee was 0-for-2 with a pair of walks, ending his six-game hitting streak.
Although the Reds kept Lee in check, they couldn't stop Berkman from getting another game-turning hit. Berkman has 35 career homers and 99 RBI against Cincinnati, his best numbers against any team, and delivered again even though he was in a deep slump, batting only .184.
Sampson gave up five hits in seven innings, including solo homers by Brandon Phillips and Josh Hamilton.
The 25-year-old Hamilton has been so sensational during his comeback from drug addiction that manager Jerry Narron reconfigured his lineup this week to keep Hamilton on the field.
Hamilton's homer was his fourth in only 24 at-bats, the latest sign that the former No. 1 overall draft pick is rounding into form after more than three years away from the game.
Phillips didn't dally on his homer, which barely cleared the wall in front of the Reds' bullpen in center field. A night earlier, he prematurely broke into a home run trot on a fly that hit the wall, drawing a comment from Narron.
Sampson, who has split his time between the bullpen and the rotation, improved to 3-1 in five career starts. ... Ken Griffey Jr. perfectly timed Luke Scott's fly ball in the second inning and caught it at the top of the right field wall. ... The Reds have decided to go with two catchers for now. They activated OF Norris Hopper from the 15-day DL and designated C Chad Moeller for assignment. That leaves them with David Ross and Javier Valentin to catch.