PITTSBURGH -- Each of the Pittsburgh Pirates' bats seemed to produce some noise Tuesday, but Gregory Polanco's was just a bit louder.

Polanco recorded an RBI in each of his first three at-bats, pelting balls to left field and dead center, while all the Pirates took turns pounding the Houston Astros for 11 hits. Meanwhile, Ivan Nova breezed through a six-hitter.

All of that added up to a 7-1 victory for Pittsburgh over Houston at PNC Park.

After belting his 18th home run of the season to left field in the third inning, Polanco smashed his team-leading 19th off left-handed reliever Tony Sipp two innings later to give the Pirates a 6-0 lead through five.

"I guess I'm getting stronger," Polanco said. "My swing is getting better, shorter and quicker. Experience, too. The more swings you take, the better you get every day. I think it's about experience and now, I'm learning more in the league every day."

It marked the second time this season and in his career Polanco hit two home runs in a game. He also hit two with three RBIs against the St. Louis Cardinals on July 4.

Pittsburgh added a seventh run on an error off Polanco's groundout in the seventh.

Nova used 98 pitches to cruise through his fourth career complete game. Only Marwin Gonzalez, who recorded three hits, challenged him.

"He was very efficient with his pitches," Pirates manager Clint Hurdle said. "He threw a lot of really good sinkers against a very good-hitting team with a lot of right-handed hitters and he locked them up with the ball away."

Alex Bregman and Jose Altuve started the ninth with back-to-back doubles to score Houston's lone run. Astros manager A.J. Hinch credited Nova's location for Houston's offensive struggles.

"It looked like he had a lot of life on his ball. I think he had, what was it, 15 ground ball outs or outs on the ground?" Hinch said. "So, he really pounded the bottom of the strike zone. He had a ton of movement. We couldn't really get the ball on the barrel and mount any sort of rally against him.

"When he needed a ground ball, he got it and then he mixed in a few breaking balls, a few changeups and moved the ball around. But pitching with a lead, he did a good job of pitching to contact on the ground."

The Pirates (63-60) ended a four-game skid in emphatic fashion, while the Astros (65-61) saw their four-game winning streak come to an end. Houston scored 35 runs during the streak.

Pittsburgh immediately pounced on Astros right-hander Joe Musgrove, recording six consecutive hits to begin the first inning and producing four runs.

After Adam Frazier singled to center for Pittsburgh's first hit, Matt Joyce, Andrew McCutchen and Polanco took turns belting fastballs into the left-center-field gap. Joyce doubled toward PNC Park's left field notch, scoring Frazier from first, before McCutchen sent a double into the same spot to give the Pirates an early 2-0 lead.

Polanco quickly smacked a pitch into the gap but only managed a single that was good enough to drive in McCutchen. David Freese followed Polanco by singling to center, and Josh Bell drove in Polanco with a single down the left field line, which he unsuccessfully tried to stretch into a double, extending Pittsburgh's lead to 4-0.

Musgrove, a 23-year-old rookie, struggled coming off the worst performance of his young major league career.

In his last start against the Baltimore Orioles on Thursday, Musgrove allowed eight runs on 11 hits and three home runs in a 13-5 loss. He had surrendered three runs combined across his previous two starts while going seven innings in each.

Musgrove seemed to settle in the second inning Tuesday, retiring the Pirates in order, but let one get away to Polanco in the third. Polanco grooved an opposite-field home run to left on a 3-1 pitch to balloon Pittsburgh's advantage to 5-0.

Musgrove left after four innings, his shortest outing in five appearances this season. He allowed five runs on eight hits.

"The starter's job is to go out there and set the tone of the game and anytime you go out there and have a first inning like that, it kind of sucks the wind out of you," Musgrove said. "I had the right plan going out there. I just didn't execute. That's kind of been the problem, just execution. I've been through failure before and I know I'm going to go through it again, so I'll process things, learn from it and be ready to go next time out."

NOTES: Astros 3B Luis Valbuena will undergo season-ending surgery on his injured right hamstring in the next few days. Valbuena, who has not played since July 26, hit .260 with 13 home runs and 40 RBIs in 90 games this season. ... Houston OF Marwin Gonzalez started in left field while Teoscar Hernandez shifted from left to center. ... The Major League Baseball Players Alumni Association awarded Pirates 3B David Freese with the Heart and Hustle Award. The award, which is presented to one player from each MLB team, "honors active players who demonstrate a passion for the game of baseball." ... Pirates OF Starling Marte did not play Tuesday and was replaced by Gregory Polanco in left field. Matt Joyce took Polanco's place in right and batted second, Marte's usual spot in the lineup. ... Pittsburgh 1B Josh Bell started for the third consecutive game. He made his first major league start Sunday.