Houston, TX (SportsNetwork.com) - George Springer capped his return to the lineup with a go-ahead solo home run in the bottom of the eighth inning that lifted the Houston Astros to a 4-3 victory over the San Francisco Giants.

Springer, activated from the 7-day disabled list Wednesday after being cleared from a concussion he sustained while making a running catch last week, hammered a full-count fastball from Jeremy Affeldt (0-2) over the home-run line in left center to snap a 3-3 tie.

"I was thinking to get something up in the zone and hit it hard," Springer said.

Houston had battled back from a 3-1 deficit on solo homers from Jason Castro and Luis Valbuena in the fifth and sixth innings, respectively.

The Astros also had to overcome an injury shortened start from Brett Oberholtzer in his season debut. The left-hander was removed after just three innings due to a blister on his pitching hand, the same injury that landed him on the DL to begin the campaign.

Five Houston relievers stepped up to hold the Giants scoreless over the final four innings, however. Chad Qualls (1-2) was awarded the win for a perfect top of the eighth, while Luke Gregerson worked around a leadoff double from Brandon Crawford in the ninth to record his eighth save and help the Astros earn a split of this two-game interleague series.

Buster Posey went 3-for-5 with a homer and knocked in all three San Francisco runs, but grounded back to Gregerson with the tying run at third for the final out.

"Our execution got us tonight. Little things, productive outs and missed hit- and-runs. Those things catch up to you in a close ballgame," Giants manager Bruce Bochy said.

Houston halted a four-game home losing streak and a string of seven consecutive losses to the Giants, though Gregerson had the outcome in doubt up until the end after entering with a 4-3 lead courtesy of Springer's blast.

The Astros closer was aided by a baserunning gaffe from Crawford, who attempted to take third on Nori Aoki's sharp grounder that followed his double. Shortstop Jonathan Villar's throw was in plenty of time to erase the potential tying run, a play that proved more important after Angel Pagan moved Aoki to third with a two-out single.

Posey then stepped up and swung at the first pitch, but managed only a dribbler to the mound that Gregerson fielded and tossed to first to end the game.

San Francisco's Tim Hudson had cruised through the opening three innings and was staked to a quick 1-0 edge when Matt Duffy drew a walk off Oberholtzer in the first, stole second and came around on Posey's single to center.

The veteran righty struggled in the fourth, however, as back-to-back walks to Valbuena and Springer were followed by a Colby Rasmus single that knotted the score.

Oberholtzer was able to complete the third inning before being relieved by Samuel Deduno, who managed to work out of a bases-loaded jam in the fourth but couldn't escape trouble an inning later.

After Pagan tripled to begin the fifth, Posey crushed a hanging curveball deep into the left-field seats for a 3-1 San Francisco lead.

Castro got a run back in the bottom half with his second homer in as many nights, and Valbuena belted another Hudson offering into the home bullpen to tie the game in the sixth.

Hudson permitted three runs on six hits over 5 1/3 innings, while Oberholtzer was reached for a run on five hits in his abbreviated outing.

Game Notes

Houston posted its first win over the Giants since June 14, 2012, when the Astros still resided in the National League ... The Astros improved to 18-0 this season when scoring at least four runs ... Duffy, who drove in a career- best five runs in Tuesday's series opener, has gone 11-for-24 with eight RBI over a seven-game hitting streak ... Pagan and Crawford each collected two hits for San Francisco ... Houston optioned reliever Kevin Chapman and outfielder Robbie Grossman to Triple-A Fresno to make room for Springer and Oberholtzer.