HOUSTON -- Something about the Arizona Diamondbacks always seems to bring out the best in Roy Oswalt.
Oswalt pitched eight strong innings to stay unbeaten against Arizona, and pinch-hitter Jose Vizcaino's two-run single with the bases loaded in the eighth sent the Houston Astros to a 3-0 win over the Diamondbacks on Tuesday night.
"Roy threw the ball extremely well tonight," Astros manager Phil Garner said. "He got in a really nice groove and he finished out strong in the eighth."
Oswalt (5-4) allowed only five hits -- all singles -- struck out eight and walked one to improve to 4-0 with a 0.90 ERA in four career starts against Arizona.
Brad Lidge pitched the ninth for his eighth save in nine chances, sending Houston to its season high-tying third consecutive win.
The Astros, who totaled 13 runs in the previous two games, resumed their struggles at the plate against Arizona right-hander Javier Vazquez (4-3). But Houston got just enough offense for the victory.
Morgan Ensberg and Jason Lane led off the fourth inning with singles, and Adam Everett followed with a sacrifice fly to center to give Houston a 1-0 lead.
The run was greeted by a loud, sarcastic cheer from the crowd of 27,156 -- the Astros entered the game 27th in the majors in runs.
With the bases loaded in the eighth, Vizcaino entered to pinch hit and drove in two runs off Arizona reliever Mike Koplove to add a little more cushion for Lidge.
"We need those kind of hits because we haven't been scoring a lot of runs," Vizcaino said. "The pitching's been great but we haven't helped them out much."
That was just enough for Oswalt, who has held opponents to two runs or fewer in seven of his last eight starts. Oswalt and Lidge also extended Houston's streak of scoreless innings to 24, the longest in the majors this season.
The Astros have notched back-to-back shutouts, including Sunday's 9-0 win over San Francisco, for the first time since last June 8-9 against Seattle. It's their first consecutive shutouts at home since July 27-28, 2002, against Pittsburgh.
Houston's starters have a 1.11 ERA over the last eight games.
"When you've got a rotation like we have, we've got a chance to keep rolling," Everett said.
Vazquez allowed one run and seven hits in seven innings, striking out five. He also extended his streak to 30 innings without a walk.
"He pitched well enough to win," Diamondbacks manager Bob Melvin said. "He's pitched like that the last four or five times out there. This was just a matchup of two dominant right-handers."
The Diamondbacks dropped to 9-7 in one-run games, including 3-3 on the road.
The Astros ended a three-game home losing streak to Arizona. ... Houston's streak of 24 innings without allowing a run is its longest since a 32-inning streak in 1997. ... Astros rookie Todd Self, called up from Triple-A Round Rock when Jeff Bagwell went on the DL last week, scored the first run of his career. ... Arizona 3B Troy Glaus was back in the lineup after sitting out Sunday with a left knee injury. He went 0-for-4 with two strikeouts. ... Arizona CF Jose Cruz Jr., who went to high school and college (Rice) in Houston, went 2-for-4 in his Houston homecoming. His father, Jose Cruz, is the Astros' first base coach and played in Houston from 1975-87.