SAN FRANCISCO -- For a team that hadn't won a home series in more than two months, facing the National League's best team since the end of May and its trio of aces didn't figure to be the way to get out of a slump.
But San Francisco has been the team getting the stellar starts.
Lowry (7-11) followed Jason Schmidt's eight scoreless innings Friday, striking out eight and retiring 18 of the final 20 batters he faced.
"We faced two good pitchers the last two days and did pretty well," first baseman J.T. Snow said. "We got good pitching. It all starts on the mound."
Lowry was the sharper pitcher this game, continuing his strong stretch since the All-Star break. Keeping the Astros off-balance with his off-speed pitches, the only hit he allowed came when Jason Lane singled off the left-field wall to lead off the second inning. Lowry lowered his ERA to 1.81 in five starts since the break.
After throwing 21 pitches in the first inning, Lowry tried to be more aggressive and needed just 85 pitches over his final six frames. Lowry left because his left elbow tightened up but said he wouldn't miss a start.
"I threw a lot more fastballs inside today, which in turn opens up the outside part of the plate for my changeup," Lowry said. "I was able to hit my spots for strikes."
San Francisco, which has the worst home record in the National League, has won its first series at SBC Park since taking two of three from the Los Angeles Dodgers from May 24-26.
"It is satisfying to get success at home. Maybe we can get some more respect at home, too," manager Felipe Alou said in a thinly veiled reference to a radio talk-show host on the Giants flagship station who made racial remarks about the team's Latino players earlier this week.
Houston avoided its second consecutive shutout when Morgan Ensberg hit a two-run homer in the ninth inning against Tyler Walker. Before Ensberg's 29th homer, the Astros hadn't gotten a runner as far as second base.
"If they keep getting pitching like that, they're going to win a lot of games," Astros manager Phil Garner said.
After scoring just six runs in the first 25 innings of a three-game series against Colorado's beleaguered pitching staff, the Giants have posted back-to-back wins over two of the best starters in the league.
The Giants will go for their first sweep at home since the opening week of the season when they face Roger Clemens on Sunday. San Francisco doesn't know who it's starter will be because Brett Tomko is out with a bone bruise in his right foot.
Oswalt had allowed two earned runs or fewer in 13 of his previous 16 starts. He gave up more than that by the third inning against the Giants and allowed four runs -- three earned -- and nine hits in seven innings.
Ray Durham led off the second with a single, advanced to second on a sacrifice fly and scored on a single by Alfonzo. After Matheny singled, Lowry sacrificed the runners to second and third.
Omar Vizquel then hit an RBI single to center to make it 2-0. Randy Winn followed with a grounder to second base. With Vizquel running right in front of him, Craig Biggio bobbled the ball for a run-scoring error.
The Giants added another run in the third when Durham singled, stole second and scored on another hit by Alfonzo.
"They nickled and dimed me," Oswalt said. "It's one of those games where you have to kind of take it in stride. I didn't have my best stuff. I had average stuff. It's just one of those days when they were able to find the holes."
- Oswalt was 15-1 in his career in August before the loss.
- Houston 1B Jeff Bagwell, who had right shoulder surgery June 7, hit off live pitching for the third straight day. The Astros are optimistic Bagwell could return as a pinch-hitter in September after originally thinking he could be sidelined for the season.
- San Francisco OF Moises Alou (tight right hamstring) missed his fourth straight game.