Gaudin (2-1) had his second good start in place of the injured Ryan Vogelsong, allowing two runs on five hits in six innings. The Giants right-hander, normally a long-relief specialist, struck out seven and walked one intentionally. One of Arizona's runs scored on Gaudin's balk. Scutaro and Belt each had a solo shot off Tyler Skaggs (1-1), who gave up five runs on eight this in five innings.
The Giants won two of three in Arizona to move within 1 1/2 games of the first-place Diamondbacks in the NL West.
Scutaro also singled twice, scoring two runs.
The Giants got to Skaggs for four singles and a walk before he recorded an out.
San Francisco opened the game with singles by Andres Torres, Scutaro and Buster Posey to make it 1-0. Hunter Pence walked, then Joaquin Arias' RBI single put the Giants up 2-0.
Gaudin retired the first eight batters before Cliff Pennington's one-out single in the third. Skaggs reached when Gaudin bobbled his sacrifice bunt attempt, then threw wide to first, but Gerardo Parra flew out to center and Didi Gregorius struck out to end the threat.
Scutaro's solo shot high off the foul pole in left for his second home run put San Francisco up 4-0 in the fourth.
Arizona broke through with two in the fourth. Miguel Montero singled with one out, then after Martin Prado was called out on strikes, to his vehement objection that the pitch was low, Jason Kubel singled to put runners at first and second. Montero scored on A.J. Pollock's bloop single, then Kubel came home from third when Gaudin was called for a balk.
San Francisco made it 6-2 in the eighth when Gregor Blanco tripled to the right field corner off Matt Reynolds and scored on Torres' sacrifice fly to left.
There were several standout defensive plays, two of them in the first inning.
First, Arizona second baseman Cliff Pennington made a nifty over-his head catch of Juan Perez's pop foul. Then Perez, in his major league debut, slammed into the wall in front of the swimming pool in left-center as he caught Paul Goldschmidt's deep drive. Perez got up slowly but jogged off the field and stayed in the game.
Pence, the right-fielder, caught another shot by Goldschmidt to the fence to end the fifth inning.
In the fifth, Parra barehanded Torres' hit to right field and threw to second to force out Gaudin on a nice catch by shortstop Gregorius. Gaugin had reached on the first baseman Goldschmidt's third error of the season.
NOTES: Goldschmidt was 0-4 and ended his string of RBIs in eight straight games, which had tied a franchise record. ... Giants manager Bruce Bochy said he was still awaiting results of the MRI on 3B Pablo Sandoval, who left Saturday night's game in the third inning after aggravating a left foot strain that sidelined him for two games last week. ... The three games against San Francisco were Arizona's only home contests in a stretch of 17. ... The Giants travel to Pittsburgh, sending RHP Tim Lincecum (4-5, 4.75 ERA) to the mound against the Pirates' Gerrit Cole in Monday night's opener. Arizona goes to Los Angeles, where LHP Wade Miley (4-5. 4.92) starts for the Diamondbacks against LH Clayton Kershaw (5-4, 1.93). ... With 38,222 on hand Sunday, the total for the weekend was 120,338 - most at Chase Field for a three-game series since Sept. 23-25, 2011, also against the Giants.
