BOSTON -- In just a few minutes, Boston's hitters turned a slow offensive night into an easy victory.
"We came to life. We were able to combine some base on balls with some base hits," manager John Farrell said. "It seemed like we got a couple of pitches up in the zone from (Scott) Feldman. The first time or two in the order he kept us in check and kept us off balance."
Matt Dominguez hit a two-run homer for Houston, which opened a 10-game road trip with its fourth loss in five games.
Allen Webster (3-1) gave up four runs -- three earned -- and five hits in six innings for Boston.
"I grinded through it and then they took over with the seven runs," the soft-spoken Webster said. "I can't complain at all."
Trailing 4-1, the Red Sox chased Feldman (6-9) during their biggest inning of the season.
"It just snowballed. He was one pitch away from getting out of it, but they just continued to find holes and continued to keep the line moving," Houston manager Bo Porter said. "Before that he was in complete command of the game and really was commanding both sides of the plate."
Pedroia's ground-rule double bounced off the chalk on the right-field line and caromed into the stands. Ortiz, Mike Napoli and Will Middlebrooks each had an RBI single before Jackie Bradley Jr. drew a bases-loaded walk from reliever Darin Downs that pushed Boston ahead 5-4.
Feldman was charged with seven runs on nine hits in 5 1/3 innings. And he felt he was in trouble before the big inning.
"I think it actually started probably before that," he said. "It felt like I had turned into a one-pitch guy. I really had command of only one pitch, from like the fourth, fifth, sixth, something like that."
The Astros scored single runs in the second and third before Dominguez's homer made it 4-0 in the fourth. Dominguez homered into the Green Monster seats after Jon Singleton's leadoff walk.
Boston sliced it to 4-1 when Pedroia scored on Yoenis Cespedes' double-play grounder.
Astros: OF Alex Presley (strained right oblique) won't play in games and will only get treatment for a couple of days because he had some discomfort during his minor league rehabilitation assignment at Class A Tri-City.
Red Sox: Cespedes was back in the lineup after coming out of Wednesday's game with a bruised right hand, but fouled a ball off his shin and left in the ninth. ... Farrell said outfielder Allen Craig, on the 15-day disabled list with a sprained left foot, will take batting practice the next few days before being sent on a rehab assignment.
LHP Dallas Keuchel (10-8, 3.07 ERA) pitches Friday for the Astros after losing his last start, giving up five runs in six innings at home against Texas. It was his worst start in more than a month.
Red Sox RHP Clay Buchholz (5-7, 5.98) looks for his second strong start against Houston this season. He struck out 12 in a complete-game victory at Minute Maid Park on July 13.
WHAT A THROW
Porter joked that he'll be shutting down injury updates on rookie outfielder George Springer (right quadriceps), who had a setback in his rehab and was shut down for two weeks. Springer has been out since July 19. "In 13 days we can talk about him again," Porter said, smiling.
NO NEED TO PACK FOR A WHILE
The Red Sox opened an 11-game homestand, their longest in more than three years. After four games against Houston, they have four with the Los Angeles Angels and three with Seattle.