PHOENIX -- After the Giants' infield botched a sixth-inning rundown Monday that generated another Arizona Diamondbacks run, manager Bruce Bochy couldn't choke back his mingled sarcasm and dismay.
"I looked at Ronnie," Bochy said, referring to bench coach Ron Wotus, "and said, 'Can we start Spring Training over?' It was like we didn't have Spring Training."
Indeed, it wasn't. The Giants were officially charged with two fielding errors that spawned four unearned runs in the fourth inning off Madison Bumgarner and lapsed into other miscues, including the aforementioned rundown, that helped Arizona assume a four-run lead through six innings.
But frustration quickly turned to redemption for the Giants on Opening Night. They offset their myriad of mistakes with a four-run seventh inning that tied the score, vaulted ahead on Buster Posey's two-run, ninth-inning homer and held on for a 9-8 triumph that seemed absolutely improbable, given San Francisco's mistake-filled start.
Said Posey, "I think we want to be a team that keeps grinding and keeps clicking. It was fun to be able to do that coming out of the chute tonight."
Posey's homer, which broke a 7-7 tie, provided the margin that ended the Giants' three-game losing streak in season openers, all on the road.
"He's on a different level, man," Bumgarner said. "He's been that good since Day One."
If Posey settled the outcome, first baseman Brandon Belt may have defined it. Belt's error, a mishandling of Mark Trumbo's ground ball, opened the fourth. He also took part in the failed rundown by chasing Paul Goldschmidt toward second base before flipping the ball ineffectually to shortstop Brandon Crawford.
But Belt atoned with an offensive flurry that featured a sixth-inning homer, a seventh-inning single and a one-out hit in the ninth that preceded Posey's decisive, two-out drive off Addison Reed.
"It's kind of easy to put your head down," Belt said. "But we didn't. We pushed forward."
Michael Morse's single christened the Giants' big seventh, most of which unfolded with two outs. Arizona starter Brandon McCarthy needed one out to escape the inning unscored upon before Ehire Adrianza's pinch-hit double scored Joaquin Arias. That ended McCarthy's evening and launched a streak of five consecutive hits, including Angel Pagan's RBI double, Belt's hit, Pablo Sandoval's bizarre RBI single that he blooped off shortstop Chris Owings' glove after ducking from reliever Oliver Perez's inside pitch, and Posey's single. That loaded the bases for Hunter Pence, who coaxed a walk from Brad Ziegler that forced in Belt with the tying run.
Bochy praised Adrianza, the rookie participating in his first season opener, for providing an essential hit. McCarthy felt differently, believing that he had slipped a called third strike past Adrianza.
"There was a call there in the seventh that changed the entire outlook of the game," McCarthy said. "Obviously, we all have to execute after that point, but that's a juncture, that's a pitch that you're not rewarded for, so that kind of leaves a bitter taste."
Sergio Romo yielded Miguel Montero's leadoff homer in the ninth inning but held on to save the Giants' triumph, stranding Owings on second base by striking out pinch-hitter Eric Chavez and inducing A.J. Pollock's game-ending popup.
The Giants achieved their first comeback from a four-run deficit in a season-opening win since 1968, when Willie Mays, Jim Ray Hart and Jesus Alou contributed key ninth-inning hits in a 5-4 decision over the Mets.
The Giants couldn't have anticipated such drama Monday at Chase Field. They sent Bumgarner to the mound, fresh off a dominant Spring Training performance. The 24-year-old became the team's third-youngest starter in a season opener -- both in San Francisco-era history and among all left-handers in franchise annals.
But Bumgarner's defense betrayed him, and Bochy lifted him for a pinch-hitter after the dreadful fourth.
"I'm not looking for a four-inning start," said Bumgarner, who still derived some satisfaction from his ability to cope with the distractions accompanying a season opener.
"I felt really relaxed," Bumgarner said. "None of the hoopla bothered me."