HOUSTON -- For a team that hadn't scored more than six runs all season, the San Francisco Giants might view their 8-1 win over suddenly the slumping Houston Astros on Tuesday as a wealth of riches.

The Giants went 32 games into a season without scoring more than six runs in a game for the first time since 1914, but they were so proficient Tuesday that they really didn't need the two-hit pitching and first career complete game of rookie right-hander Chris Heston.

Heston (3-3) gave up one run and did not walk a batter while striking out 10. He retired the final 22 batters he faced after a solo home run by Astros catcher Jason Castro with two out in the second.

His 46 1/3 innings and 39 strikeouts rank as the most among National League rookie pitchers.

"I just tried to keep my pitches down in the zone, and I was able to change speeds well tonight," said Heston, who threw just 107 pitches. "I threw a lot of curveballs and changeups for strikes, and I was able to get some swings and misses with them. It was all about throwing strikes and sticking to the game plan. I had some good innings back to back."

Heston got all the run support he needed from fellow rookie third baseman Matt Duffy, who hit a three-run double in the second and a two-run single in the fifth two days after getting the game-winning hit in the ninth against the Miami Marlins. He went 3-for-4 and raised his average from .273 to .300. Duffy is hitting .455 (10-for-22) with runners in scoring position.

"I like Duffy when he's out there, but he's also a nice weapon to have when he's on the bench," Giants manager Bruce Bochy said. "It's good to reward a guy who had a big hit for us (on Sunday) with a start tonight, and he came through for us again."

The standout performances from Heston and Duffy ended the Astros right-hander Collin McHugh's 11-game winning streak. McHugh had the longest active run in the major leagues, but he surrendered seven runs (four earned) on seven hits in 4 2/3 innings.

McHugh's streak dated back to Aug. 12, 2014, and covered 15 starts. He was one win shy of tying the franchise record, 12-game streaks by right-handers Mark Portugal (1993) and Wade Miller (2002).

"I didn't have good stuff tonight, and it showed," McHugh said. "I had nothing behind the ball today. Our job as pitchers for this team is to go out and throw the ball as well as I can for as long as I can, and I didn't do my job today. The streak is over -- now we can stop talking about it."

The Astros (20-13) lost for the sixth time in eight games after a 10-game winning streak. Center fielder Jake Marisnick, who was moved to the leadoff spot to create more offense, had the Astros' only other hit.

"We just had an empty game, but we are not too far away from stringing together some hits and breaking out," Astros manager A.J. Hinch said. "We needed to have more discipline at the plate tonight. Hester did a good job of moving the ball around and keeping us of balance."

Houston has just three hits and 21 strikeouts in its past two games combined.

San Francisco (17-16) jumped on McHugh for three runs in the second inning on Duffy's no-out, bases-loaded double.

After Castro's home run, the Giants batted around and chased McHugh in the fifth with a five-run outburst.

Two Astros errors kept the inning alive. The first error, on a hard-hit grounder by catcher Buster Posey, was deflected but not corralled by third baseman Luis Valbuena and loaded the bases.

McHugh struck out first baseman Brandon Belt on a full count before right fielder Justin Maxwell slashed a grounder into the hole between third base and shortstop that was fielded by shortstop Marwin Gonzalez, who threw to second to try to get the force out. Second baseman Jose Altuve could not come up with the throw, which bounded into short right field to allow two runners to score.

Shortstop Brandon Crawford added a ground-rule double, and Duffy singled home two runs, expanding the Giants' lead to 8-1.

"Those two big innings really made the difference in the game," Hinch said.

NOTES: The Giants scored just 101 runs through their first 32 games, their fewest since 1985 when they had 93 during the same span. San Francisco began the night averaging 3.16 runs per game, next to last in the majors (Philadelphia, 94). ... 1B Brandon Belt, a Texas resident, is 15-for-34 (.441) in his past eight games with six doubles, a triple, two RBIs and four walks. ... After a 2-2 road trip that ended Sunday, the Astros own a 12-4 record away from Minute Maid Park, tied for the best road start through 16 games in franchise history. The mark was set in 2004.