Giants 8, Diamondbacks 4: Madison Bumgarner hit a grand slam and pitched 6 1/3 solid innings as San Francisco took the rubber match of the three-game series from visiting Arizona.

Buster Posey added a grand slam of his own in support of Bumgarner as they became the first batterymates in major-league history to hit grand slams in the same game. Bumgarner (10-7) finished with two hits and two runs scored at the plate while yielding four runs on 10 hits from the mound.

Vidal Nuno (2-6) made his second start since joining Arizona and pitched well aside from Posey’s blast, yielding four runs on six hits in five innings. Cody Ross homered and Martin Prado drove in a run on three hits as the Diamondbacks assured themselves of being in last place in the National League West at the break.

Arizona took a 1-0 lead on Prado’s RBI single in the third but the Giants broke through against Nuno in the fifth. Bumgarner began the rally with a double to left and Pablo Sandoval’s single loaded the bases in front of Posey, who got a 1-0 fastball in the lower half of the zone and launched it into the stands in left.

Matt Stites came on for Nuno in the sixth and loaded the bases on a single, an error and a walk before Bumgarner turned on a first-pitch, 98-mph fastball and lined it into the seats in left for his second grand slam of the season and third home run. Ross homered with one out in the seventh and Nick Evans’ RBI double cut it to 8-4 and chased Bumgarner from the contest.

GAME NOTEBOOK: Bumgarner joined Atlanta's Tony Cloninger (1966) as the only pitchers to hit two grand slams in one season. ... The last time the Giants scored as many as eight runs came in an 8-0 win over the St. Louis Cardinals on June 1. … San Francisco 1B Brandon Belt was scratched from the lineup due to back stiffness. … Ross’ blast was his second of the season and first since May 18 against Los Angeles.