ST. LOUIS -- Jeff Samardzija knew he had no choice, not if he wanted the San Francisco Giants to win on Saturday.

He had to match what St. Louis Cardinals starter Carlos Martinez was doing to his teammates, which was basically render their bats useless. A combination of late-moving sinkers and breaking pitches enabled Martinez to breeze through nine scoreless innings on 93 pitches.

Samardzija did his part, helping San Francisco outlast Martinez before emerging with a 3-1, 13-inning win at rainy Busch Stadium.

Rookie third baseman Christian Arroyo snapped the scoreless tie with a bases-loaded, two-run double off the base of the left-center-field wall in the 13th, and Nick Hundley added a sacrifice fly as the Giants (19-25) won for the seventh time in eight games.

It wouldn't have been possible without Samardzija, who looked nothing like the pitcher who entered the game with a 5.26 ERA. Over eight innings, he gave up five hits and no walks while fanning eight in probably his best outing of the year.

"I knew I'd have to be stingy because (Martinez) has great numbers here," Samardzija said. "It was rather rhythmic the way he was pitching. I'd get my five minutes in the dugout between innings and then I'd go back out there."

Working as though he were double-parked, Martinez reached the ninth inning on just 73 pitches, using no more than 12 in each of the first eight innings. He retired the first 10 hitters before Joe Panik singled in the fourth, then mowed down 12 straight before a one-out infield hit by Eduardo Nunez in the eighth.

Martinez pumped his fist as he walked off the mound after he induced an inning-ending groundout from Panik in the ninth, marking the first time as a major-leaguer he completed nine innings. Martinez gave up just two hits and a walk, whiffing five.

"What great stuff he had tonight," San Francisco manager Bruce Bochy said of Martinez. "You were just hoping you could find a way to get a run in."

That finally happened in the 13th, the only inning in which the Giants pushed a man into scoring position. One-out singles by Buster Posey, Brandon Crawford and Nunez loaded the sacks for Arroyo, who in his four previous at-bats grounded out three times and fouled out.

Behind 1-2 against Kevin Siegrist (0-1), Arroyo played spoiler with six two-strike pitches, eventually running the count full. Finally, on the 12th pitch of the at-bat, Arroyo picked on a changeup on the plate's outer half, scoring Posey and Crawford with the only runs San Francisco needed.

"I was just trying to get a pitch I can do damage with," Arroyo said. "I wanted to make sure I was on the fastball yet protecting on the other pitches. I've been trying to do too much the last couple of nights, so I tried to relax."

Teamed with Hundley's scoring fly ball to right, it was more than enough to offset Stephen Piscotty's two-out RBI single off Mark Melancon in the bottom of the 13th. Melancon got Matt Carpenter to fly out to center for the final out and his eighth save.

Carpenter was a central figure in Nunez's big defensive play in left field that started the bottom of the ninth. Carpenter lashed a 2-2 pitch from Josh Osich off the wall for a sure double but tried to stretch it into a triple. Nunez chased the ball down in the grass and erased Carpenter on a close play.

That wiped out St. Louis' best chance of rewarding Martinez with the win his performance merited. Instead, the Cardinals (21-19) lost their fourth consecutive game.

"He had it all tonight," Cardinals manager Mike Matheny said of Martinez. "It was just a shame we couldn't do anything with it."

Hunter Strickland (1-1) fired two scoreless innings to pick up the win.

NOTES: St. Louis recalled RF Stephen Piscotty (hamstring) from his rehabilitation assignment at Double-A Springfield and inserted him into the lineup, and he went 1-for-5. Piscotty was injured May 4 against Milwaukee. ... San Francisco INF Conor Gillaspie (back spasms) finished 1-for-3 on Friday in his first game of a rehab stint with Triple-A Sacramento. He has been on the 10-day disabled list since May 11. ... The Cardinals traded 1B Matt Adams to Atlanta about an hour before game time Saturday, receiving corner infield prospect Juan Yepez from the Braves. Adams, batting .292 with a homer and seven RBI in 48 at-bats, should play every day for the Braves with 1B Freddie Freeman (wrist) on the DL for an extended period.