Updated

Houston, TX (SportsNetwork.com) - Robbie Grossman's two-run homer capped the six-run first inning that propelled the Houston Astros to an 8-1 win over the Oakland Athletics on Wednesday.

Six of Houston's eight hits came during the first-inning rally against struggling A's starter Jason Hammel.

Hammel (0-4) has lost all four of his starts since he was acquired from the Cubs in a deal that featured All-Star Jeff Samardzija. He was lit up in this one, departing with one out in the fifth inning after allowing all eight runs and two homers.

"Obviously I can be frustrated and upset, but you gotta have a short memory," said Hammel. "Because I'm going to have the ball again in five days. If you carry it with you, it can get a lot worse."

In contrast, Houston starter Dallas Keuchel (10-7) was superb en route to his AL-leading fourth complete game of the season. The left-hander yielded just a run on four hits over nine dominant innings and earned his first career win against Oakland in five starts.

Keuchel said he was lucky to get early swings from the A's batters. He threw 111 pitches, including 70 strikes.

"I looked up and it was the eighth inning," Keuchel said.

Jon Singleton also homered for the Astros and Jose Altuve extended his hitting streak to 12 games with a single in the sixth.

Houston won two of three in the series.

After Altuve flied out to open the bottom of the first, Enrique Hernandez and Jason Castro singled. Marc Krauss grounded into a fielder's choice to plate the first run and following a walk to Singleton, Matt Dominguez and Carlos Corporan hit back-to-back singles. Two scored on Dominguez's line drive to center because of rookie center fielder Billy Burns' error.

Grossman followed Corporan's base knock with a two-run homer, his fourth of the season.

The last A's starter to give up six runs in the first inning was Sean Gallagher on May 18, 2009.

Josh Donaldson hit a leadoff homer in the top of the second to produce Oakland's only run.

Hammel allowed just a walk with no hits over his next three innings, but couldn't finish the fifth. Castro drew a leadoff walk and after Krauss grounded out, Singleton chased Hammel from the game with his shot to left.

Game Notes

Houston's Chris Carter was a late scratch with flu-like symptoms ... Altuve has hit in 17 straight games against the Athletics ... No one in the game had more than one hit.