San Francisco currently leads the wild-card race by a half-game over the Chicago Cubs and two over Houston with 11 games to play.
The Astros have won 19 of 24 to move within striking distance of the Giants.
Oswalt’s stellar second half has played a big role in Houston’s turnaround. The 27-year-old right-hander is 10-2 with a 3.22 ERA in 14 starts since the All-Star break.
However, Oswalt aggravated a rib cage injury on Friday in a 2-1 win over Milwaukee. He stayed in long enough to get the win, allowing eight hits and two walks while striking out five over seven innings. He said the injury has bothered him all year and he has taken three cortisone shots and three Novocain shots.
“It’s just something you deal with,” Oswalt said. “Hopefully, we can try the painkiller again next time and get me through it. It takes your breath away as soon as you release the ball. I’ve been doing the cortisone shots and I don’t want any more of them. Hopefully, the Novocain shots will be enough next time.”
Bonds has owned Oswalt throughout the right-hander’s four-year career, going 3-for-3 with two doubles, a homer and two walks.
Bonds took a back seat to his teammates on Tuesday.
Bonds went 0-for-3 with a walk as the Giants moved within a game and a half of first-place Los Angeles in the NL West.