The D-backs are still in the hunt for the second Wild Card spot in the National League, but Arizona does not have much margin for error over the final three weeks of the regular season.
After coming within one strike of Giants right-hander Yusmeiro Petit throwing a perfect game against them on Friday, the D-backs trail the Reds by eight games for the final postseason berth.
The D-backs can't afford to lose much more ground, and will look to remain in the postseason hunt on Saturday with Brandon McCarthy on the mound in the third game of a four-game series at AT&T Park.
McCarthy has struggled recently, though, and is 1-6 with a 5.92 ERA over his last seven starts. The right-hander tossed a complete game on Monday against the Blue Jays, but still took the loss to drop to 3-9 on the season. McCarthy has faced San Francisco once this year, charged with four runs on eight hits in six innings May 1 in Arizona.
In order to keep pace with the Reds, the D-backs will have to go through Giants hurler Matt Cain, who will come off the disabled list to make his first start since Aug. 22. Cain was hit by a line drive on the right forearm in that start and went on the DL for the first time in his nine-year Major League career. He threw 90 pitches in a bullpen session on Monday.
Cain won 16 games last season, and at least 12 in each of the past four years, but is just 8-8 in 26 starts in 2013. The right-hander has a 4.43 ERA, the highest of his career. But Cain has been successful against Arizona in the past, and is 14-6 with a 3.39 ERA lifetime against the D-backs.
San Francisco is 15 games under .500 and last in the NL West, so the Giants are playing the role of spoiler this September.
D-backs: Eaton thriving at top of order
• Adam Eaton is becoming a productive leadoff hitter in his second season in the Major Leagues. The outfielder has a .373 on-base percentage when he bats leadoff, compared to .333 when he's in the No. 2 hole.
"He's more comfortable," D-backs manager Kirk Gibson said. "He's starting to play more baseball and getting an idea how you use his tools."
• Shortstop Chad Owings made his first Major League start on Friday. Owings, ranked the No. 3 prospect for Arizona and No. 84 overall in the Majors according to MLB.com, was the Pacific Coast League MVP and Rookie of the Year with Triple-A Reno this season before being promoted to the D-backs.
Giants: Posey sidelined by broken finger
Buster Posey is progressing from a fractured right ring finger, but the Giants catcher will likely rest for a few more days.
Posey was injured on Tuesday in San Diego and has not played since. He took swings off a tee on Friday, though he will likely need to take batting practice before he's cleared to play.
"It feels better today," Posey said Friday. "Some of the swelling has gone down."
In 130 games, Posey is hitting .309 with 14 homers, 32 doubles and 69 RBIs.
• Arizona first baseman Paul Goldschmidt is 26-for-81 (.321) in 23 career games at AT&T park with five homers and 20 RBIs.
Austin Laymance is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.