Shields, Heston Face-Off iIn Rubber Match

(AP) -- James Shields didn't fare well against the San Francisco Giants in October, but he's been extremely tough when facing them in the regular season.

The right-hander looks to bounce back from his first losing decision with the San Diego Padres by improving to 3-0 against the Giants during the regular season Thursday at AT&T Park.

Shields (7-1, 3.75 ERA) tossed a four-hitter in a 5-0 victory Aug. 9 in his first appearance versus San Francisco with Kansas City. However, he posted a 7.00 ERA while going 0-2 in the World Series against the Giants.

Sporting a new uniform, Shields again shined while striking out seven in seven innings and yielding just a home run to Joaquin Arias and two other hits in a 10-2 home victory over San Francisco (39-34) on April 11.

"It's a new team," Shields said. "My job is to beat whoever I'm opposing."

Arizona became the first opponent this season to hand Shields a loss Friday, when he allowed four runs, eight hits and walked a season-high four in six innings of a 4-2 defeat.

"I think he'd like to take back a few pitches here and there," manager Pat Murphy told MLB's official website. "It wasn't his best outing but he's a fighter."

Buster Posey is 0 for 7 in the regular season versus Shields, but his grand slam helped San Francisco even this series with Wednesday's 6-0 victory. It's the only hit in 12 at-bats over the last four games for the veteran catcher, who started at first base and could spend more time there to take pressure off his body and benefit his offense.

"Anybody who's seen this team for a while knows we're willing to change the roles if it does help the team win," Posey said.

Trying to win a 10th home series in the last 11 versus San Diego (35-39), the Giants hand the ball to Chris Heston (7-5, 3.83).

The right-hander has yielded three runs and seven hits each and hasn't completed six innings while splitting his two starts since no-hitting the New York Mets on June 9. He lasted 5 2-3 innings in a 9-5 win at Dodger Stadium on Friday.

Though Heston has been far from dominant in those two outings, his teammate continue to believe in him and manager Bruce Bochy might have enough faith to keep the rookie in the rotation when Jake Peavy and Matt Cain return next month.

"He's stepped in and pitched some big games for us," Posey said. "Every time he takes the ball, I think he expects to have a good outing."

The result wasn't what Heston hope for May 6, when he allowed five runs and matched a career high with 11 hits in five innings of a 9-1 home loss against the Padres. He's allowed 22 baserunners over nine innings in two career starts versus San Diego.

Cory Spangenberg and Alexi Amarista are a combined 7 for 10 versus Heston but are 1 for 6 in this series. Justin Upton walked three times against Heston in May, and had two of the Padres' five hits as they were shut out for a major league-high 11th time Wednesday.

"You're pressing a little bit," said Murphy, who is 3-5 since replacing the fired Bud Black. "We've got to drop that tension and play with that freedom. At the same time, they feel that urgency."

Updated June 25, 2015