They looked like a first-place team that deserved to be there in a 9-4 victory over the Giants, clinching yet another series victory on their road to the postseason.
Brandon Webb pitched around a few trouble spots over seven solid innings and Arizona started its biggest rally, a four-run outburst in the sixth, when No. 8 hitter Augie Ojeda reached on a bunt single.
There were no celebrations on the field, but the Diamondbacks officially have one fewer team to worry about in the National League West. They eliminated the Giants, who are 161/2 games out with 16 to play.
"Well, we knew it," Giants manager Bruce Bochy said. "We'll keep pushing here and try to finish strong. That's all we can do at this point."
The Diamondbacks widened their lead in the NL West to 31/2 games over San Diego. They lead Los Angeles and Colorado by six games.
They got what they needed from their ace in a rubber game. Webb retired the first nine hitters on just 22 pitches. By contrast, Giants starter Jonathan Sanchez needed 80 pitches to record the same number of outs.
Sanchez showed his potential and his deficiencies all at once. He struck out seven over three innings, most of them on his live-wire fastball. But he also gave up consecutive home runs to Mark Reynolds and Chris Snyder in the second inning.
Reynolds hit a changeup and Snyder crushed a 92 mph fastball into Andres Galarraga territory, three rows from the top of the left field bleachers at the base of the Coke bottle.
"I didn't have command today," Sanchez said. "It was 3-2 to a lot of guys."
Sanchez couldn't retire Arizona's 6-7-8 batters leading off the fourth, hitting Snyder with a pitch before allowing singles to Stephen Drew and Ojeda. Bochy, mindful of Sanchez's escalating pitch count, went to his bullpen.
"He worked hard," Bochy said. "He had good stuff. He just made a lot of mistakes along the way."
Scott Atchison did well to reduce the damage, holding Arizona to one run on a sacrifice fly before escaping the inning.
The Giants rallied for two runs off Webb in the fourth. Dave Roberts tripled and scored on Nate Schierholtz's single. Then Schierholtz stole second base, took third on a sacrifice and scored on a ground out.
The Giants had to be pleased with the way Schierholtz went after the reigning Cy Young Award winner.
"If he makes a mistake over the plate, I expect to hit it," Schierholtz said. "I chased a few changeups out of the zone too. I'll know what to look for next time."
The Diamondbacks blew open a one-run game in the sixth after Ojeda bunted his way aboard and Webb tried to advance him on a sacrifice. Catcher Bengie Molina tried for the out at second base, but Ojeda slid ahead of the throw.
Scott Munter, who got out of a bases-loaded, one-out situation a night earlier, couldn't repeat the trick. Justin Upton hit a two-run double and Conor Jackson followed with a two-run single.
The Giants crowded the dugout rail with anticipation in the ninth inning as Erick Threets made his major league debut.
Threets, a Granada High School product who conquered wildness to become an effective reliever at Triple-A Fresno, walked the first two batters and they scored on Stephen Drew's two-out ground-rule double.
Threets was clocked as high as 96 mph on the stadium radar display.
"I've been in the minor leagues for seven years, but these last nine days up here seemed like an eternity," said Threets, who left tickets for friends and family every day. "I was happy to get through it."
Contact Andrew Baggarly at firstname.lastname@example.org.