DENVER (AP) — Chad Bettis threw a two-hitter for his first career complete game, Carlos Gonzalez hit a grand slam as part of a six-run third and the Colorado Rockies beat the slumping San Francisco Giants 6-0 on Monday.

Bettis (12-7) was perfect until Eduardo Nunez singled with two outs in the fifth inning. The right-hander struck out seven and walked none.

San Francisco intentionally walked Nolan Arenado to face Gonzalez in the third. Gonzalez lined a fastball from Matt Moore over the fence in right-center for his second grand slam of the season.

An erratic Moore (2-4 with Giants, 9-11 overall) allowed six runs in 2 2/3 innings — his shortest outing of the season. He walked four and threw two wild pitches.

The Giants had the best record in baseball at the All-Star break, but things have unraveled. They’ve gone a major league-worst 16-31 since then, lost their lead in the NL West and are now trying to hang on to a wild-card spot.

Bettis was stellar in the best outing of his career, keeping the ball in the infield most of the game. He surrendered a leadoff double to Trevor Brown in the sixth, but worked his way out of the jam.

After getting Angel Pagan on a grounder to end the game, Bettis held up his right fist in triumph. He tapped his chest and pointed up to the sky.

Bettis is 6-2 in 12 starts at Coors Field this season.

Moore, who was acquired from Tampa Bay on July 31, struggled with his control in the third. He walked the first two batters of the inning, including Bettis when the pitcher tried to put down a bunt. That paved the way to the decisive inning.

Two batters after Gonzalez’s drive, Nick Hundley hit a solo homer to give the Rockies a 6-0 lead.

TRAINER’S ROOM

Giants: C Buster Posey received a day off after spending 13 innings behind the plate Sunday during a loss in Chicago against the Cubs. “I’ve got to keep an eye on these guys and keep them fresh,” manager Bruce Bochy said.

Rockies: OF Charlie Blackmon was out of the lineup for a third straight game with tightness in his lower back. … Manager Walt Weiss isn’t ruling out the return of rookie SS Trevor Story (torn ligament in left thumb) before the end of the season. Story has been on the DL since Aug. 2. “If that happens, great,” Weiss said. “The logistics of it all probably make it a long shot.” … OF Ryan Raburn left the game in the sixth with a bruised left foot.

A GRAND TIME

It was Gonzalez’s sixth grand slam with the Rockies, tying him with Dante Bichette and Andres Galarraga for second-most in team history, according to the Rockies. Todd Helton leads with seven.

POWER STRUGGLE

Part of the problem for the Giants has been a lack of power, with just 36 homers in the second half. Some of their better long ball hitters — Brandon Crawford, Brandon Belt and Posey — have gone a combined 243 at bats without leaving the yard.

“I can’t explain it for you,” Bochy said. “Hopefully, that means we’ll hit a few from this point on.”

UP NEXT

Giants: RHP Jeff Samardzija (11-9, 4.06 ERA) is 1-1 with a 2.30 ERA in two starts against Colorado.

Rockies: LHP Tyler Anderson (5-5, 3.43 ERA) has allowed three or less runs in 12 of his 15 starts.