PHOENIX -- The Arizona Diamondbacks went from stunned to elated in one wild ninth inning.
"You talk about a range of emotions. What a game," Arizona manager A.J. Hinch said. "We scored a lot of runs [five] with two outs and that's a good sign."
"He put a good swing on a bad pitch," McClellan said, "and that's what big league hitters do."
Adam LaRoche doubled home two runs in the first inning and added an RBI single in the seventh for Arizona. Young hit a solo homer in the fourth.
The Diamondbacks' bullpen, with the worst ERA in the majors at 7.33 entering the day, couldn't hold the lead. Felipe Lopez doubled leading off the ninth and closer Chad Qualls was charged with an error when he bobbled a toss to first base on Colby Rasmus' grounder.
Pujols hit an RBI single and, one out later, Randy Winn drove in a run with a single. Vasquez came on for Qualls and uncorked a wild pitch that allowed Pujols to score the tying run.
Moments later, Young ended it.
"Adrenalin was flowing and at that point, you're just trying to see it and hit it," Young said. "He gave me a good pitch to hit. I knew it had a chance."
Arizona starter Edwin Jackson got through 6 2/3 innings and scattered eight hits before departing with runners on second and third. He hasn't beaten the Cardinals in five appearances.
St. Louis ace Chris Carpenter wasn't sharp with his command through his six innings. He had to wiggle out of two bases-loaded situations in his last two innings of work and walked a season-high five. He struck out eight and allowed six hits.
The Diamondbacks got two runs in the seventh off reliever Dennys Reyes. Stephen Drew hit a leadoff double and scored on LaRoche's single. Montero then hit an RBI double high off the center-field wall.
Montero caught his first full game in two months after a long stint on the disabled list with a partially torn meniscus in his right knee.
Pujols lined a two-run double in the seventh off reliever Aaron Heilman, with both runs charged to Jackson. Pujols was 2 for 11 in the three-game series and finished the team's six-game road trip 3 for 22.
The Cardinals went 1-5 on their road trip through Los Angeles and Arizona.
"Tough loss and tough road trip," manager Tony La Russa said. "We gave ourselves a great chance and I thought we were going to pull it off but we didn't."
Diamondbacks LHP Dontrelle Willis has a minor infection in his left hand after splitting a nail during his last start, though Hinch said it can't get worse. Willis will be available out of the bullpen as a situational lefty when the Diamondbacks are in Boston starting Monday. Carpenter tied a career high with two hits.