PHOENIX -- This Micah Owings thing is getting to be a habit.

Just when matters looked bleakest on Wednesday for the Diamondbacks against the Astros, their savvy-hitting, right-handed pitcher was plucked off the bench again by manager Bob Melvin to pinch-hit with two out in the sixth inning, a runner on second and his club down by two runs.

Owings homered for the fifth time in 79 big league at-bats, but for the first time as a pinch-hitter, nailing the first offering from reliever Dave Borkowski over the right-field fence to tie the score and help send the D-backs on to a come-from-behind 8-7 victory at Chase Field. And with that, Arizona finished April at 20-8 and 11-3 at home -- both Major League-leading marks.

"You have your bench and then you have an extra guy who you don't mind running up there against righties or lefties or anyone in between," Melvin said. "And the way he's swinging, [sending him up there] wasn't even a tough decision."

Who that ambidextrous "anyone in between" might be, Melvin wasn't divulging at this point, but a frustrated Astros manager, Cecil Cooper, would like to find him.

Houston chased D-backs left-hander Randy Johnson after four innings, building leads of 4-0 and 6-2 against him before the home team came roaring back.

Cooper used five pitchers in relief of starter Shawn Chacon, who lasted all of five innings. In the fateful sixth, with the Astros leading, 7-5, Stephen Drew doubled to open the inning against left-hander Wesley Wright, who retired the next two batters. The right-handed-hitting Owings was sent in to hit for Brandon Medders, and Cooper countered with the right-handed Borkowski.

It didn't take more than a split second to figure out which manager made the right move.

"We can't get the stinking pitcher out, we're in trouble," Cooper said after the game. "My goodness, a two-run lead and we can't even get out of the stinking inning. That's unacceptable, and it won't happen again, I can promise you that. You get these guys down, you've got them 4-0, 6-2, and we let them back in the game. It won't happen again. It definitely won't happen again."

It's not as if the Astros haven't prepared for the situation and gone over scouting reports about what Owings has accomplished as a hitter. This year alone, he's hitting .421 (8-for-19) with a double, the homer and three RBIs. And last year, he hit four homers in 60 at-bats.

Owings, who's slated to start on Friday night here against the Mets, rolled his right foot this past Saturday at San Diego while stepping on second base as he legged out a double. He said he's still taking treatment on the ankle and was noticeably limping on Wednesday.

"We rarely go over a pitcher in our meetings when we talk about how to approach the opponents' hitters," Astros catcher Brad Ausmus said. "We went out of our way to discuss him and to talk about how to pitch him because we knew he could hit and knew he had power. We were well aware of it. That being said, he still hurt us."

It was the first pinch homer by a pitcher in the big leagues in more than four years. Milwaukee's Brooks Kieschnick last did it against Arizona's Matt Mantei on April 22, 2004. But it was the last thing on Owings' mind as he strode to the plate after chats with his coaches and amid the commotion of a pitching change.

"I talked to [Rick] Schu and Gibby [Kirk Gibson] just to get a little idea of what I was going to be seeing," Owings recalled. "They said to look for a fastball that would get back over the middle of the plate. It ended up being a slider that kind of backed up. I just put a good swing on it. What a blessing when I saw it go out."

To top it off for Borkowski, Chris Young quickly doubled and Eric Byrnes followed with a single to drive in the go-ahead run, meaning that three of the four batters reached base safely with disastrous results.

For the Astros, that is.

"All [Borkowski's] got to do, he's got one right-handed hitter to get out, and that happens to be a pitcher," Cooper said. "And we can't make a pitch to get him out. And on the first pitch. It's unacceptable. And I won't stand for it no more."

For the D-backs, it was all smiles.

"It seems like the more at-bats he gets in a shorter period of time the more comfortable he is at the plate," Melvin said about Owings. "We're hitting him more in regular [batting practice] groups to try to keep him sharp for that reason. He's on a roll a little bit offensively right now."