BOSTON -- The run support Ryan Dempster lacked in his previous two starts came in abundance Tuesday night.
Pedroia drove in four runs on three hits and a sacrifice fly. Mike Napoli added two RBIs and every Boston batter finished with at least one hit.
Dempster (5-8) allowed two runs and six hits over six innings, leaving with an 8-2 lead and picking up his first victory since June 9.
"We have an incredible offense. So you just go out there and worry about doing your job. It's just making pitches and executing pitches," Dempster said. "The wins come as a team more than an individual. That's all I care about is that when I start, we win the game. I want to give us a chance to win the game and was able to do that tonight. And we put up a lot of runs."
Dempster got himself in and out of trouble in the first, walking Dexter Fowler to lead off the game. DJ LeMahieu's attempt at a sacrifice bunt turned into an infield single as it rolled toward third base without a Boston player fielding it. Dempster got Carlos Gonzalez to pop out to third, then Michael Cuddyer grounded into a double play to end the threat.
"I thought the key was in the first inning," Red Sox manager John Farrell said.
Boston responded with two runs on three hits in the bottom of the first and led the rest of the way.
The Red Sox had at least three hits in every inning until the fifth, when they finally went hitless but still got a runner on base on a two-out walk to David Ortiz. It was also the first inning in which Boston failed to score after roughing up Juan Nicasio (4-4) early.
"It's a good hitting club," Colorado manager Walt Weiss said. "You've really got to command your stuff with that lineup or they make you pay."
Wilin Rosario had three hits for the Rockies, including a solo homer in the second all the way out of Fenway Park. Michael Cuddyer extended his career-best hitting streak to 22 games, longest in the majors this season, with a single in the fourth. He finished with two hits.
But those were the high points for the Rockies in a game that lasted 3 hours, 40 minutes.
Nicasio had his worst start of the season, lasting only 2 1/3 innings and allowing seven runs -- six earned -- on 12 hits. He walked two and struck out two. He had never allowed more than eight hits in a start this season and the Red Sox had that matched after two innings, taking a 5-1 lead with a pair of runs in the first and three more in the second.
"He looked like he struggled to find any rhythm or tempo tonight," Weiss said. "He was in bad counts and that's a tough lineup to get through when you're in bad counts. You're sitting in fastball counts and they know you're throwing your fastball, they don't miss it."
The Red Sox tagged Nicasio again in the third, ending his night after Pedroia's RBI single gave Boston 12 hits with two outs still to go in the inning. Adam Ottavino inherited runners at first and second, but got the Rockies out of the jam by striking out Ortiz and getting Napoli on a fly to center.
Boston added a run in the fourth after Stephen Drew tripled to center field on a hit he thought was a home run when it bounced high off the top of the wall. The umpires ruled the ball was in play and Drew was stuck briefly at third. The umpires spent several minutes looking at video replays before returning to the field and signaling that it was going to stay a triple.
Boston fans booed loudly at the call, but quickly forgot about it when Iglesias doubled to left and Drew trotted home to increase the lead to 8-2.
Nolan Arenado had three hits and an RBI for the Rockies.
Dempster's only glaring mistake came in the second inning on a 3-1 slider to Rosario, who drove it out of Fenway Park for his 12th home run of the season. The solo shot cleared the Green Monster in left field and all the signs above it, landing in a raised parking lot across the street.
"I didn't see it," Dempster said. "I think it hit a car on the turnpike, probably. It happens."
The Red Sox topped their 19 hits in a 17-5 rout of Texas on June 4. ... The two-game interleague series wraps up Wednesday afternoon with RHP Roy Oswalt (0-1) facing Boston RHP John Lackey (4-5). ... Nicasio started the season 3-0, but hasn't won since beating San Francisco on May 19. ... Napoli's two RBIs gave him 52 before the midway point of his first season in Boston. ... The Red Sox optioned struggling third baseman Will Middlebrooks to Triple-A Pawtucket before the game. Middlebrooks has hit .192 in 53 games for Boston this season, missing 16 with a lower back strain. ... The Red Sox also recalled right-hander Pedro Beato from Pawtucket after placing left-hander Franklin Morales on the DL with a strained muscle on the left side of his chest.