SAN FRANCISCO After blowing an early four-run lead, the Giants put together another come-from-behind victory, walking off against the Diamondbacks on Marco Scutaros single in the 10th inning.Starting pitching reportBarry Zito finished a 1-2-3 first inning with back-to-back strikeouts, the first swinging and the second looking, and struck out the side in the second to work around Paul Goldschmidts one-out double. Zito didnt have his strikeout pitch working in the third and fourth innings, but still held the Diamondbacks scoreless as he worked with a 4-0 lead.The Diamondbacks got to Zito in the fifth inning, though, as Miguel Montero led off the inning with a single and trotted home on Chris Johnsons no-doubt home run to left. Zito stranded Chris Young on second base after his two-out double to keep Arizona from getting within a run of tying the game.Justin Upton and Jason Kubel put together back-to-back singles to open the sixth and knock Zito from the game. Guillermo Mota, a frequent follow-up to short Zito starts, allowed both of his inherited runners to score.Zitos final line: 5 IP, 7 H, 4 ER, 0 BB, 6 K. He threw 59 of his 89 pitches for strikes.Zito was 36-3 in his Giants career when receiving at least four runs of support while in a game. The Giants offense gave him that magic number in the first, but Zito uncharacteristically didnt return the favor.Bullpen reportBruce Bochy turned to Guillermo Mota with two men on and no outs in the sixth inning and the veteran right-hander had an outing to forget. He got lucky when Paul Goldschmidts drive to left-centerfield hopped over the wall for a ground-rule double, keeping the tying run at third. That run would come across anyway, when Chris Johnson tallied his third RBI on a sacrifice fly. But the Diamondbacks werent done beating up on Mota. Former Giant Cody Ransom worked a walk and pinch-hitter Willie Bloomquist followed with a single to drive in Goldschmidt.With Arizona now leading 5-4, Bochy turned the ball over to George Kontos, coming off his first career win in Houston. Kontos, who has admitted putting more pressure on himself when he inherits another pitchers baserunners, didnt do Mota or the Giants any favors, as he allowed back-to-back singles. Kontos got Justin Upton to fly out to right to end the inning, but not before Arizona batted around for a five-run inning and a 7-4 lead.Brad Penny got the call in the seventh and was in immediate trouble after a leadoff double followed by a walk. But Penny danced out of danger by getting Miguel Montero to fly out and ended the inning with a blind-luck grab of a screaming comebacker for a double play.Shane Loux allowed an Arizona insurance run in the eighth, but was hit hard in what couldve been a much uglier inning if not for the defensive efforts of Pablo Sandoval and Angel Pagan.Recent call-up Jean Machi, a right-hander who saved 15 games for the Fresno Grizzlies this season, made his major-league debut in a one-run game and held his own. He put sure-handed shortstop Brandon Crawford to work, inducing back-to-back infield pop ups before Jason Kubel hit a routine ground ball to short to end the inning.El Mechon blared over the AT&T Park speakers as Sergio Romo ran in from the bullpen to pitch the 10th inning. He struck out the first two Diamondbacks he faced before inducing a weak ground ball to third from Gerardo Parra to end the inning.At the plateThe Giants came into Mondays game averaging just 3.45 runs per home game, ahead of only the Seattle Mariners. They raised that average with their first inning output alone.Angel Pagan lined out on the first pitch, but the Giants strung four consecutive hits together to score first. Marco Scutaro started the rally with a single and Pablo Sandoval kept the line moving with another single. Buster Posey followed with a drive to deep right that Arizonas Justin Upton appeared to have a beat on. But Upton watched as the ball sail over his head and bounced off the wall past him and towards the infield, allowing Scutaro to score easily. Upton had to hustle again when Hunter Pence one-upped Posey with a two-RBI triple into the right-centerfield alleyway. Sanchez drove in Pence with an infield single for a 4-0 San Francisco lead.After the four-run first, the Giants were held scoreless until the seventh inning, when Aubrey Huff led off with a pinch-hit single. Pagan grounded into a fielders choice and the baserunner swap paid off, as the faster Pagan advanced to second on Scutaros grounder to third and came around to score on Sandovals single up the middle.The Giants added two more runs in the eighth with a two-out rally to cut the Diamondbacks lead to one. Pence struck out looking to open the frame and Xavier Nady grounded out to second, but Hector Sanchez and Brandon Crawford hit back-to-back doubles and pinch-hitter Brandon Belt drove in the other Brandon with a single to right. Pinch-runner Gregor Blanco, in for Belt, represented the tying run, but Pagan lined out to right to end the threat.The Diamondbacks turned to J.J. Putz in the ninth, fresh off a blown save in Los Angeles on Sunday, and Scutaro greeted him with a leadoff double to left. Sandoval hit a weak ground ball to second to advance Scutaro and set the stage for Posey. With the tying run 90 feet away and the Arizona infield playing in, Posey laced a ground ball past diving third baseman Chris Johnson for a double and a brand new ballgame. Posey was left stranded to keep the game tied, however, after Putz intentionally walked Pence and struck out Nady and Sanchez. The double was Poseys first career game-tying hit in the 9th inning or later.Crawford led off the 10th inning with a towering chopper behind the pitchers mound that he beat out for an infield single. Big Brett Pill followed with his first career sacrifice bunt to advance the game-winning run into scoring position. Pagan pushed Crawford 90 feet closer to ending the game with a groundout to first base, and Scutaro came through with his 11th career walk-off hit, which was nearly identical to Poseys grounder past diving third baseman Johnson.The Giants finished 9-for-15 with runners in scoring position, including three doubles, a triple and all nine of their RBIs.In fieldBrad Penny made the play of the day, even if it required more instinct than skill, when he snagged Chris Johnsons comebacker in the heel of his glove for one out, then lobbed the ball back to first for a double play.Pablo Sandoval made a pair of nice plays in the eighth to keep the Diamondbacks from putting up a crooked number. With Cody Ransom on third, Sandoval fielded a sharp ground ball off the bat of Chris Young and threw home to Hector Sanchez, who chased Ransom back to third, where Sandoval got the ball back and applied the tag. The next batter, Aaron Hill, ripped a liner right at Sandoval, who stood his ground and hit the dirt to complete the catch.Angel Pagan also helped limit Arizona to one run in the eighth, as he ended the inning with a leaping catch on the warning track just in front of the avocado tree past the centerfield wall.On the basesGregor Blanco took off for second base in the eighth after coming in as a pinch-runner, but Angel Pagan hit the pitch foul. No other Giant attempted a stolen base against Diamondbacks catcher Miguel Montero.AttendanceThe Giants announced a crowd of 42,045 for their 150th consecutive regular season sellout.Up nextThe Giants continue their series with the Diamondbacks on Tuesday night with right-hander Ian Kennedy (12-11, 4.27 ERA) starting opposite fellow right-hander Ryan Vogelsong (12-7, 3.02 ERA). First pitch is scheduled for 7:15 p.m. on Comcast SportsNet Bay Area and Giants Pregame Live kicks off at 6:30 p.m.