SAN FRANCISCO -- Jeff Samardzija insists he rarely has had as much fun watching teammates pitch as he is having with the San Francisco Giants.

Of course, what really makes it enjoyable is being able to duplicate what he saw when it is his turn to take the mound.

Samardzija combined with three relievers to hold the San Diego Padres in check Tuesday night, allowing the Giants to pull away late for an 8-2 victory.

Buster Posey broke a sixth-inning tie with an RBI double, Brandon Crawford drove in four runs, and minor league call-up Jarrett Parker belted a two-run home run as the Giants recorded their eighth consecutive win in the intrastate rivalry.

"It's good to get a cushion," said Giants manager Bruce Bochy, whose team was coming off consecutive 1-0 victories.

Those games were pitched by Madison Bumgarner and Johnny Cueto, who always pitch the days before Samardzija.

Samardzija is enjoying the rotation.

"We definitely feed off each other competitive-wise," Samardzija said. "I haven't watched guys pitch this closely for a while.

"Johnny and Bum, the success they've had. You don't want to be the sour grape, for sure."

Jon Jay's home run off Samardzija in the top of the sixth drew the Padres even at 1-1 before Joe Panik led off the bottom of the inning with a walk off San Diego starter Andrew Cashner (2-4).

Panik advanced to second on Matt Duffy's slow roller to the pitcher, then scored the tiebreaker standing up on Posey's liner down the left field line.

After Brandon Belt flied to center field for the second out, Crawford singled to right field, and Posey beat Matt Kemp's throw to the plate for a 3-1 lead.

"They haven't been clicking offensively," Bochy said of the Giants, who scored more than five runs for the first time since May 6. "It was good to see the guys break out. That was a tight ballgame."

Kemp, who allowed Hunter Pence's high fly ball to drop in front of him to end the Giants' 1-0 win Monday, continued his nightmarish series Tuesday, getting thrown out trying to stretch a first-inning single into a double and an eighth-inning double into a triple.

The latter was particularly troublesome as it came when he was the leadoff hitter in the eighth with the Padres trailing just 3-1. He was initially ruled safe at third, but Bochy used replay to get a call reversed for the second time in the game, short-circuiting a possible San Diego rally.

"More than anything, we're pleased with the way he swung the bat tonight," said Padres manager Andy Green, attempting to deflect some of the criticism from Kemp. "He smoked that ball to right-center (in the eighth). Some good things to build on there."

The Giants went on to extend the lead in the bottom of the inning on a three-run triple by Crawford and the homer by Parker, who was promoted from Triple-A Sacramento earlier in the day.

"Hopefully that inning gets the guys going," Bochy said. "Maybe we'll keep the line moving better."

Samardzija (7-2) became the second Giants starter in two nights to record a seventh win in his first 10 starts of the season, joining Cueto. He allowed one run on six hits and three walks in 6 2/3 innings, striking out seven.

The win was Samardzija's third of the season against the Padres, who were limited to three hits when the first-year Giant beat them 3-1 last week.

"It's fun baseball to watch," the veteran said of his defensive support, especially in the outfield. "Anytime you're getting doubles and triples turning into outs, that's a big momentum swing for the pitcher."

Left-hander Josh Osich and righties Cory Gearrin and George Kontos followed Samardzija with 2 1/3 innings of one-run, three-hit relief.

The Padres' second run came off Kontos in the ninth on pinch hitter Hector Sanchez's two-out RBI single.

Cashner, activated from the disabled list earlier in the day, took the loss, giving up three runs in six innings. He allowed four hits and four walks while striking out one.

Crawford had a triple and a single, Denard Span a double and a single, and Gregor Blanco two singles for the Giants, who won for the 12th time in their past 13 games.

Crawford raised his season RBI total to 26.

Kemp and Alexei Ramirez had two hits apiece for the Padres, who lost their third in a row.

Jay's homer provided the Padres' first run of the series after they were blanked on a total of just five hits by Cueto and Samardzija in the first 14 innings.

The homer was his second of the season.

The Giants got on the board first in the third inning thanks to the first overturned call on review.

Blanco led off the inning with a single and was sacrificed to second by Samardzija.

With Padres shortstop Ramirez standing on second base expecting a pickoff throw, Span grounded a single through the vacated position, and Blanco was given the green light to head home.

A strong throw by Padres left fielder Melvin Upton Jr. initially was ruled to have gotten Blanco at the plate. However, that call was reversed on replay, giving Span his 17th RBI and the Giants a 1-0 lead.

"Tough loss," Green said. "Some better swings today than yesterday for sure, so it's good to build on that."

NOTES: The eight-game winning streak over the Padres equals a Giants franchise record, set initially from June 21, 1987, to April 9, 1988. ... The Giants have won 10 in a row over the Padres at AT&T Park dating back to last season. ... Padres RHP Andrew Cashner fell to 0-6 in his career at AT&T. ... In order to activate Cashner from the disabled list, the Padres optioned reliever RHP Kevin Quackenbush to Triple-A El Paso. ... The Giants placed LF Angel Pagan (strained left hamstring) on the 15-day DL and recalled OF Jarrett Parker from Triple-A Sacramento. ... Giants RF Hunter Pence (strained right hamstring), hero of Monday's win in a pinch-hitting role, did not play Tuesday. Manager Bruce Bochy said he expects Pence to be limited to pinch-hitting duties in the series finale Wednesday.