HOUSTON — Before the game, Pittsburgh's Adam LaRoche told friends on the Astros that they were going to play 18 innings.

If not for his big hit in the 15th, they might have.

LaRoche's three-run homer triggered a five-run 15th inning and the Pittsburgh Pirates beat Houston 8-3 Friday night to them with the Astros in the cellar in the NL Central Division.

"I was having flashbacks of an 18-inning game we played here two years ago," LaRoche said of a game he played while with the Atlanta Braves. "Me and Lance Berkman each hit grand slams in that one and Chris Burke won it with a homer.

"I was joking with Lance and (Brad) Ausmus that we would do this. I kept saying, 'Trust me, we're going to play 18 today. I can feel it."'

Instead, Nate McLouth walked and stole second and Freddy Sanchez reached on third baseman Mike Lamb's error to start the rally and set up LaRoche's 19th homer.

The shot barely went out into the right corner of the Crawford boxes in short left field.

"I didn't think it was out," LaRoche said. "My bat felt like it weighed 45 ounces at that point. I knew I hit it all right but I also knew they were playing back so I thought they'd catch it.

"But it just found that little corner."

Carlos Maldonado added a sacrifice fly to drive in another run and Jose Castillo had an RBI single to make it 8-3.

The Pirates have won three straight and seven of nine and moved out of last place in the Central by three percentage points ahead of the Astros.

Reliever Shane Youman (3-4) pitched the last two innings for Pittsburgh. It was only his third relief appearance of the year after seven starts. In the bottom of the 15th, Youman loaded the bases with no outs and then struck out the side.

"I can't ask anybody to do any more than they all did tonight," manager Jim Tracy said. "There were so many different big moments.

"The at-bat by LaRoche in the 15th was so big because it was for three runs. I knew the way Shane was, it might have been tough if that's all we got. So the two more runs were big."

Only two of the 15th inning runs were earned off of reliever Travis Driskill (0-1) who pitched three innings. Driskill was making his first appearance in the majors this year. His contract was purchased Wednesday from Triple-A Round Rock.