HOUSTON -- While the Houston Astros enjoyed a typical slugging performance Wednesday, the final slugger of the evening presented quite the welcome sight.

Right fielder George Springer, back in the lineup for the first time in a week, bashed a solo home run in the bottom of the eighth inning to complete the Astros' rally for a 4-3 interleague win over the San Francisco Giants at Minute Maid Park.

Activated earlier Wednesday from the seven-day concussion disabled list, Springer drilled a one-out, 3-2 fastball from Giants left-hander Jeremy Affeldt (0-2) an estimated 409 feet to left-center field for his fifth home run of the season and the Astros' third of the game.

"It's awesome to be back and to go out there again and to fight with these guys again," said Springer, who finished 1-for-3 with a walk. "It means a lot."

Houston third baseman Luis Valbuena hit his eighth homer leading off the sixth, mimicking the leadoff homer catcher Jason Castro smacked to right-center in the fifth. Both came against Giants right-hander Tim Hudson, and Houston ended the night with an American League-leading total to 49 homers.

The Giants (17-17) led 3-1 in the middle of the fifth.

After falling behind on Springer's blast, San Francisco attempted a rally against Houston closer Luke Gregerson in the ninth, with shortstop Brandon Crawford opening the inning with a double to left field. However, Crawford was erased as the first out attempting to take third on left fielder Nori Aoki's grounder to shortstop Jonathan Villar. With two outs and runners on the corners, Gregerson completed his eighth save when Giants designated hitter Buster Posey tapped a weak grounder to the mound.

"Leadoff double, that's what you're hoping to get ... and (Aoki's) ball was hit right to his left shoulder," Giants manager Bruce Bochy said of Crawford. "If they go back, they might've had a shot at him there, so we've got to execute a little better there on both sides. Still had first and third and the right guy up there, so that's all you can ask."

Right-hander Chad Qualls (1-2) picked up the win in relief for Houston (21-13), capping a strong relief effort that featured a scoreless inning each from right-handers Will Harris, Pat Neshek, Qualls and Gregerson.

Posey proved productive in first three plate appearances. His two-out single to center field scored second baseman Matt Duffy and delivered the Giants a 1-0 lead in the first off Astros left-hander Brett Oberholtzer.

Oberholtzer made his season debut after a blister on his left index finger landed him on the disabled list, but he departed after three innings due to a blister complication.

Posey, who added another single in the third, blasted a two-run homer off Astros right-hander Samuel Deduno for a 3-1 lead in the fifth inning.

Hudson wound up allowing three runs on six hits in 5 1/3 innings.

The Astros enjoyed only modest success against Hudson in the early going, manufacturing a run in the fourth inning when left fielder Colby Rasmus followed a pair of two-out walks with an RBI single to center.

"Scoring without a homer was nice," Astros manager A.J. Hinch said. "We don't have to homer just to score. Rasmus came into the game swinging the bat well against Hudson. It was a good matchup for us, and he took what they gave him, which was a base hit away.

"That's three quality at-bats in a row that produces a run. That was big for us to get on the board."

Late in the game, the Astros flashed their power. Springer capping the display served as a reminder to what Houston missed.

"With this team, we know they're pretty aggressive with the fastball," Affeldt said, "and that's a guy that's probably all or nothing on that pitch."

NOTES: To clear a roster spot for the return of OF George Springer from the seven-day concussion disabled list, the Astros optioned OF Robbie Grossman to Triple-A Fresno after Tuesday's game. ... Giants RHP Chris Heston on Tuesday night became just the third rookie in the last 25 years to toss a complete game while allowing two or fewer hits and zero walks with 10-plus strikeouts, joining Cubs RHP Kerry Wood (May 6, 1998, against the Astros) and Cardinals RHP Shelby Miller (May 10, 2013, against the Rockies). ... The Giants signed RHP Tommy Hanson to a minor league contract. Hanson, 28, finished third in the 2009 National League Rookie of the Year balloting but was beset by shoulder injuries starting in 2011. He last pitched in the majors for the Los Angeles Angels in 2013.