Giants 6, Diamondbacks 4: Brandon Belt homered and drove in three runs as visiting San Francisco snapped its five-game losing streak.

Belt broke a 4-4 tie in the eighth with a two-out, two-run single off Brad Ziegler (1-1), who opened the inning by allowing a double to Nick Noonan. Ziegler retired the next two batters before loading the bases with consecutive walks to Gregor Blanco and Brandon Crawford.

Jean Machi (1-0) earned his first major-league victory with a scoreless seventh inning and Sergio Romo worked around a leadoff single in the ninth for his ninth save for San Francisco, which ended a six-game road losing skid. Marco Scutaro chipped in three hits and scored two runs.

Belt, who was dropped to eighth in the batting order after recording two extra-base hits in his last 10 games, crushed a solo homer off Ian Kennedy in the second to put the Giants ahead 3-0. Kennedy gave up four runs over seven innings and remained winless since opening day.

Giants starter Matt Cain allowed three home runs in an inning for the first time in his career in the fourth, when Jason Kubel blasted a two-run shot and Eric Chavez followed with a solo shot. Martin Prado capped the outburst with a two-out homer to left-center field off Cain, who gave up four runs in six innings.

GAME NOTEBOOK: Giants 3B Pablo Sandoval, who tied the game at 4-4 with an RBI single in the fifth, left the game in the sixth inning with right elbow discomfort. … San Francisco manager Bruce Bochy was ejected for the first time this season after arguing that Hunter Pence was safe on a double play to end the fifth inning. …Arizona OF Gerardo Parra went 0-for-5 to end his career-high 13-game hitting streak.