DENVER -- After six starts, Colorado Rockies rookie Chad Bettis is still waiting for his first win in the big leagues.
That's a nanosecond compared to how long journeyman Yusmeiro Petit waited to savor another major league victory.
Petit, taking the turn of injured Matt Cain, pitched six sharp innings as the San Francisco Giants beat the Rockies 5-3. The win was Petit's first in the majors since Aug. 27, 2009, against the Giants while pitching for the Arizona Diamondbacks -- four years ago to the day.
"I feel happy because I came back to this level again to win at this level," Petit said with teammate Pablo Sandoval translating.
Hunter Pence and Sandoval hit back-to-back homers off Bettis in a three-run first inning. Pence's homer was a mammoth shot that cleared the left field concourse. ESPN Stats and Information estimated the ball traveled 476 feet and was the longest homer in the majors this season. It came after a two-out single by Brandon Belt, who went 4-for-5 with four singles.
"All my hits combined probably weren't hit as hard as his," Belt said. "I heard it hit the bat and saw the trajectory, and I knew it was going to be out a long, long ways."
Pence, who prefers not to talk about himself, gave credit to Petit for setting the tone of the game and had little to say about his home run. He added that he didn't watch the flight of the ball or see it on replay.
"It was in the first inning and feels good to get some runs on the board," Pence said.
Petit (1-0) threw six innings of two-run ball. He fired first-pitch strikes to 20 of the 26 batters he faced and threw 67 of his 96 pitches for strikes. He was making his 38th major league start but just his second in the past four seasons. His lifetime record is 11-20 with a 5.43 ERA.
"He pounded the strike zone with all of his pitches and threw quality strikes," Giants manager Bruce Bochy said. "He's been around, knows what he's doing out there. He showed it tonight."
Petit was making his second major league appearance of the season and just his third in the past four years.
Sergio Romo retired the side in order in the ninth to pick up his 32nd save in 36 chances.
Bettis (0-3) surrendered four runs on nine hits in six innings. He has allowed five homers in 30 innings over his six starts.
"I think he missed a couple pitches in the zone, and we can't execute the last pitch," Rockies catcher Wilin Rosario said. "Every hitter we got two strikes, and we couldn't execute the one pitch to make an out. I think that's why he got a little bit out of control."
Petit gave up single runs in the third and fourth, slicing San Francisco's lead to 3-2. Charlie Blackmon hit a double to drive in Colorado's first run.
Rosario (3-for-4) singled home a run in the fourth with one out, but with runners on second and third, Petit got Nolan Arenado to fly out, pitched around No. 8 hitter Blackmon and walked him, then struck out Bettis.
"He's a guy that commands the fastball well," Bochy said. "He's got four pitches he can throw at any time. He's not going to overpower you, but he's got the savvy you like from a pitcher. And he comes at you. This is not any easy park to pitch in against a great lineup."
Sandoval finished with three hits, and Marco Scutaro and Hector Sanchez had two hits apiece for the Giants.
NOTES: Giants OF Andres Torres will undergo surgery Wednesday to have bone spurs removed from his left heel. Rehabilitation time is about six months, so Torres might not be ready at the start of the 2014 season. ... The back-to-back homers in the first inning by Pence and Sandoval were the first for the Giants since Sept. 20, 2012, when Sandoval and Buster Posey went deep consecutively at AT&T Park against the Rockies. ... Rockies C Yorvit Torrealba was activated from the seven-day concussion disabled list, and INF Ryan Wheeler was optioned to Triple-A Colorado Springs. ... Colorado LF Carlos Gonzalez (right middle finger sprain) took batting practice for the first time since he went on the disabled list retroactive to Aug. 5. ... Tulowitzki returned to the lineup after missing two games with soreness in his left side, and he went 1-for-3. ... Rockies CF Dexter Fowler was not in the lineup. He was still sore after he bruised his left knee sliding into second base in the first inning Monday and left the game in the second. ... Rockies RHP Roy Oswalt (left hamstring strain) threw 53 pitches in four innings in his second simulated game and then did some fielding drills afterward.