He'll try to win for the fourth time in as many starts for San Francisco in Wednesday's home matchup with the Colorado Rockies.
Petit (3-0, 2.05 ERA) was recalled from Triple-A Fresno on Aug. 23 for his second stint with the Giants (65-80) and has been stellar in posting a 1.71 ERA in winning all three starts.
His most spectacular effort came Friday when he retired the first 26 Arizona hitters before pinch-hitter Eric Chavez singled in the ninth inning just in front of right fielder Hunter Pence in a 3-0 victory.
Petit finished off the 95-pitch gem by getting the next hitter out for his first complete game. The Venezuelan says he has received numerous messages from friends and family, and will block all of that out as he gets ready for Wednesday.
"The key element now is to try and keep my concentration, to go ahead and study the hitters I have to face tomorrow and remind myself that the page that I wrote was a very beautiful page, but it's in the past," Petit told the Giants' official website. "So I have to concentrate on tomorrow's game."
The right-hander won't have to learn about a new opponent since his first start with San Francisco was a 5-3 victory at Colorado on Aug. 27 in which he allowed two runs in six innings.
Petit's five starts against the Rockies (67-79) are his most against any club. He's 1-1 with a 5.73 ERA in those outings.
Todd Helton is 4 for 9 off Petit and will likely play at AT&T Park for the last time. The Rockies stalwart is expected to retire after this season and he leads all active players with 244 hits against the Giants.
"I've always appreciated how he plays the game,'' Giants manager Bruce Bochy said.
Michael Cuddyer is 0 for 3 against Petit and remains in a tight race for the NL batting title with a .330 average - the same mark as Atlanta's Chris Johnson. Cuddyer homered twice and had four RBIs in Tuesday's 9-8 victory with a tiebreaking solo shot in the ninth inning.
The Rockies rallied from six runs down and snapped a four-game slide.
"It's a character-building win for us,'' Cuddyer said.
While Cuddyer was Tuesday's hitting star for Colorado, Pence went 4 for 5 and matched a career high with six RBIs. Pence, who has six straight 20-homer seasons, has 20 RBIs against the Rockies - the single-season high in Giants' history.
Rockies starter Juan Nicasio (8-7, 4.68) could be pitching in the wrong park Wednesday. He's 2-0 with 12 scoreless innings in two home outings against the Giants this season and has a 0-0 mark with a 5.40 ERA in two at AT&T Park, with Colorado losing both of them.
The right-hander has limited Pablo Sandoval to one hit in 12 at-bats and Brandon Belt to one in 10.