Peavy (1-0) gave up just three hits, walked three and struck out four as the Padres won the season-opener. Peavy is 3-0 with a 0.45 ERA in season openers over the last three years.
"I had pretty good stuff tonight," Peavy said. "I've got to get better."
Peavy drove in one run with a sacrifice fly in the second and another with a single in fourth.
Roy Oswalt (0-1) took the loss, surrendering 11 hits and three runs in 5 1/3 innings. Oswalt walked one and struck out six.