It was the Astros' longest game since a 4-2 win in 16 innings over the Phillies at Citizens Bank Park.
"That was a tough night," Astros manage Bo Porter said. "Obviously, offensively we couldn't get it going. I felt like we had some good pitches to hit and just didn't put good swings on them. We didn't really have too many scoring opportunities. Give their pitching staff credit."
The Phillies got seven strong innings from starter Kyle Kendrick, who allowed one run and five hits, and then had seven relievers combine to hold the Astros to one hit in eight innings. The Astros were held to six singles in 49 at-bats and struck out 17 times, including 14 times from the eighth inning until the end of the game.
"The bullpen was outstanding," Phillies manager Ryne Sandberg said. "And then Ryan Howard driving in both runs early and late. Some good defense out there and it was a good win."
Howard homered in the second inning for the only blemish against Astros starter Dallas Keuchel and went hitless in his next four at-bats, including a pair of double plays and a strikeout, before coming through in the 15th after the Astros intentionally walked Chase Utley.
"You want to go up there with a little chip on your shoulder," Howard said. "I thought the at-bat before was a little up. Two strikes, probably have to go after it a little bit. I was just trying to stay with my approach. So when they walked Chase, I wanted to get it done. I wanted to go out there and get it done."
Buchanan, who was moved back into the bullpen with Brad Peacock set to join the rotation Wednesday, threw three scoreless innings before getting himself in trouble by allowing a leadoff single to Sizemore in the 15th. Ben Revere moved him to second with a bunt, and he was still there with two outs when Howard came to the plate.
"I figured one I was going in, I was there for the long haul," Buchanan said. "Just tried to throw up zeros as long as possible and hopefully we could get a run there."
The only baserunner the Astros managed after the 10th inning came on a two-out walk to Marwin Gonzalez in the 12th. Phillies reliever Antonio Bastardo struck out six of the seven batters he faced in the 11th and 12th innings.
"You get into an extra-inning game it's one of those things where you're trying to do everything you can to push a run across and try to do everything you can to push a run across," Porter said. "I feel like our guys battled. Buchanan did a great job inning after inning, giving us a chance to come back up and score some runs. They were able to get us in the 15th."
Keuchel delivered his third consecutive quality outing, giving up one run and five hits in seven innings. In his last three starts, the lefty ace has allowed two earned runs and 20 hits in 23 innings for a 0.78 ERA in that span.
"[Kendrick] had his good stuff going today and I was trying to match him pitch for pitch," he said. "I felt like my fastball command was pretty good today and I'd like to have the slider a little bit more consistent than that, but other than that it was a great game."
As for the homer to Howard?
"It was a slider," Keuchel said. "I had faced him before in 2012 in my first year. I had some success against him, but I know he's not having the year he would like to have, but at any given point he can hit the ball out of the ballpark. Just so happened I left a slider a little bit up. He's a strong guy, so he kind of powered it out of the park."