Tim Lincecum has struggled mightily this season.

He hasn't displayed any signs of his award-winning ways and is aware of that.

"You never want to say, 'Hey, I've hit rock bottom' or anything like that," Lincecum told the Giants' website. "When things are going as bad as they are right now, you kind of got to go out there feeling like you've got nothing left to lose.

"It's been terrible. It's a terrible feeling, feeling like you've let your team down. That's the hardest thing."

Lincecum will get back to work tonight for San Francisco in the second test of a three-game series versus the Houston Astros at AT&T Park. The two-time NL Cy Young Award winner is a paltry 1-8 with a 6.69 earned run average in his last 13 starts -- the Giants are 2-11 in that time. He previously toed the rubber in a 13-2 setback at Pittsburgh on July 8 and lasted 3 1/3 innings for a second consecutive start, allowing six runs and seven hits to fall to 3-10 with a 6.42 ERA in 18 appearances.

"I have to erase this, but obviously remember it and use it to know what I don't want to go through again," Lincecum added. "When you're the weaker link, you kind of look at that and it wears on you. You try your hardest to work out of it, and that's what I've got to do."

The right-hander, who is 2-4 in eight home starts, could turn this slump around if his career record against Houston holds up. In eight career starts against the Astros, Lincecum is 5-0 with a sparkling 1.14 ERA.

Madison Bumgarner didn't have a problem with the Astros in Friday's 5-1 win and held the visitors to a run and two hits in seven innings. He struck out five and walked two, improving to 11-5 on the season and 15-2 in his last 18 starts at AT&T Park.

"It's pretty incredible what he does and the poise he has out there," said Giants manager Bruce Bochy. "For most of the pitching staff and the players, you're always gonna be a little bit more comfortable here and you usually do pitch better at home."

Buster Posey hit a two-run homer for the Giants, who ended a two-game slide and won for just the third time in 10 tries. The Giants remained only one-half game behind the Los Angeles Dodgers for the NL West lead. All-Star Game MVP Melky Cabrera had a hit in four at-bats in the win.

Posey's homer gave San Francisco nine in the past 22 games. Only 15 of the Giants' 52 home runs have come by the bay.

Houston kicked off a 10-game road trip on the wrong foot last night and lost for the 11th time in 12 tries.

Chris Snyder's solo home run in the seventh inning was all the offense the Astros could muster, while Wandy Rodriguez took the mound and allowed four runs in six innings to absorb the loss.

"They squeezed out some hits and squeezed out the early runs," said Snyder.

Rodriguez has gone at least five innings in 48 consecutive starts, marking the longest active streak in the National League. Infielder Scott Moore did not play Friday and has hit safely in each of his first nine games with the club -- a franchise record. Jeff Kemp had an eight-game run back in 2009. Moore is batting .306 with three home runs during the streak.

Lucas Harrell draws the start for the 'Stros tonight after plenty of rest and is 7-6 with a 4.56 earned run average in 17 appearances. He is 1-0 in his past two starts since losing back-to-back outings, and did not figure into the decision of an 8-7 loss at Pittsburgh on July 3. Harrell lasted five innings and gave up five runs and nine hits -- one start after tossing a six-hit shutout against San Diego on June 27.

Harrell, a right-hander, is only 2-5 in 10 road starts this season and will face San Francisco for the first time.

The Giants won two of three over the Astros at home in mid-June and have claimed 15 of the last 22 meetings overall.