PITTSBURGH (AP) -- The Pirates took advantage of Houston's dire bullpen situation.
Houston had used six of relievers to pitch 10 2/3 innings in a 17-inning, 7-6 loss Sunday in Atlanta, forcing the Astros to stick with ineffective starter Runelvys Hernandez through four rocky innings.
"With the bullpen being a little light, we just had to keep sending him out there," Houston manager Cecil Cooper said. "He had to go. We needed the innings from him. That was the bottom line."
Adam LaRoche reached base four times, scored twice and drove in a run as eight Pirates had RBIs. Jason Bay went 2-for-3 with two walks and two runs, and Xavier Nady had two hits and two RBIs for Pittsburgh, which scored more runs during the first four innings Monday than they did in being swept in three games in Milwaukee over the weekend.
Making his third start of the season since having his contract purchased from Triple-A, Hernandez (0-3) was charged with 10 runs on 13 hits and four walks in four innings.
"I tried to make pretty good pitches, but I wasn't and they took advantage and hit the ball hard," said Hernandez. "I feel bad because my teammates gave me good run support."
Carlos Lee hit his 20th home run and had three RBIs for the Astros, who have lost six of seven and fell back behind the Pirates into last place in the National League Central.
Making his season debut after having his contract purchased after the marathon game Sunday, Chad Paronto pitched the final four innings, allowing only a hit and a walk.
Pittsburgh's pitching staff has had its own problems with injuries and ineffectiveness in recent weeks. Lefty Phil Dumatrait was ineffective in his first start since a stint on the disabled list with bursitis in his throwing shoulder.
He allowed a season-high seven runs on nine hits and two walks in 3 1/3 innings, his shortest start of the season.
"My arm felt good. I just couldn't get the job done tonight," Dumatrait said.
But the Pirates bullpen pitched 5 2/3 shutout innings, highlighted by Denny Bautista (2-1), who worked 2 2/3 innings. Tyler Yates struck out four in two perfect innings, and Damaso Marte pitched the ninth for his second save, walking Mark Loretta with two outs to ruin a streak of 16 Astros in a row retired by the Pittsburgh bullpen.
"Bautista came in and did a great job. Tyler Yates was phenomenal and Marte threw the ball very well," Pirates manager John Russell said. "The bullpen saved us, being able to hold a game that offensively looked like it could go on a long time. We swung the bats really well, and the bullpen shut them down."
McLouth's home run, his 16th, went high over the stands in right in the second. Doumit's shot, his 11th, scored Luis Rivas and gave the Pirates the lead for good in the fourth.
The Pirates' offense was clicking so well early that two players had their first major league hits and RBIs. Dumatrait had a two-out run-scoring single in the first and Bautista one in the fourth.
"I think they went a combined 150 feet," Russell said. "We'll take them. They came in big situations. We weren't really expecting them but they helped us."
The Pirates, who were out-scored 22-8 their previous three contests, enjoyed a four-run first after falling behind 3-0 and answered a four-run Houston fourth with four runs in the bottom of the inning.
"We have 100 percent confidence in our offense," Doumit said. "As far as we're concerned, it doesn't matter who the other team is throwing out there. We're confident in our ability to put runs up."
After the game, the Pirates announced that outfielder Steve Pearce will be optioned to Triple-A Indianapolis to make room for right-hander Ian Snell, who will be activated from the disabled list to start Tuesday's game against the Astros. ... Tejada's first-inning run was the 1,000th of his career. ... Berkman played in his 1,300th career game. ... Dumatrait had been hitless in 24 career at-bats heading into the game. Bautista got his hit in his seventh at-bat.