DENVER -- On a night when he was far from his best on the mound, Madison Bumgarner found an unlikely way to ignite the Giants.

Bumgarner was knocked out early at Coors Field, but not before he hit a monster homer that got the offense going in a 9-8 victory over the Colorado Rockies on Tuesday. The win, coupled with the Los Angeles Dodgers' loss in Arizona, gave the Giants a six-game lead in the division with 20 games to play.

That cushion was extended on a night when Bumgarner gave up at least four runs for the fourth consecutive start. Bumgarner was charged with five runs on 11 hits in 41/3 innings, but he had two hits of his own, including a three-run homer that tied the game in the fourth.

Brandon Belt added a two-run double and solo homer and set a career-high with four RBIs. The game marked the second this season in which Bumgarner and Belt, who has six homers, went deep on the same night.

"I just don't want to be outdone by Madison Bumgarner -- at all," Belt joked. "His was a three-run dinger, but I got four RBIs so I beat him."

It wasn't as easy for Bumgarner to smile. He gave up a run in the second and three more in the third and had trouble making pitches on the outer half of the plate.

"I didn't have very good command on any of my pitches away," he said. "I pitch inside a lot, but you've got to be able to pitch away."

The Rockies took advantage, but Bumgarner erased a 4-1 deficit with a mighty swing in

"My job is to go out there and pitch, not hit," Bumgarner said. "Obviously I'm glad to do what it takes, but I wanted to pitch better."

Bumgarner ran into trouble again in the fifth and was pulled with one out and two runners on.

"He got a lot of balls up that they took advantage of, but he got us back in this game (with the homer)," manager Bruce Bochy said.

The blast also got the Giants rolling offensively. Belt's two-run double in the fifth had put the Giants on top, and the man Belt replaced at first base, Aubrey Huff, got the Giants in gear again in the sixth.

Huff hit a pinch-hit liner off the right-field wall but was forced to scramble back to first when right fielder Matt McBride came up throwing.

"He smoked that ball," Bochy said, smiling. "And did a good job of turning that double into a single."

Huff's teammates later laughed about the moment -- which included a slide that came up inches short of the first base bag -- but credited the veteran for kick-starting another rally. After Huff was replaced by a pinch runner, Angel Pagan lined a triple to right-center field that was his 12th of the year, tying a San Francisco-era franchise record held by Willie Mays and Steve Finley.

Pagan called Mays one of his idols and said the moment was one of the best of his career.

"To tie his triples record is something I'll always remember," Pagan said. "The legacy he left is something you really want to follow."

Pagan scored on a sacrifice fly, and Belt made it 9-5 with a blast to right field. The first baseman has three multi-RBI games in his last seven games and has 12 hits in his last 28 at-bats with runners in scoring position.

"I'm not changing my approach anymore," he said. "Earlier in the year, I would maybe put more pressure on myself with runners on."

In his last 36 games, Belt is hitting .350 with 14 extra-base hits and 19 RBIs.

"He's really starting to come into his own," Bochy said. "The confidence has grown in him and in the second half he's shown what kind of player he can be. That's big to add one more run and give us a cushion, which we needed."

Three relievers combined for eight strikeouts in the first 22/3 innings after Bumgarner was pulled, but Jeremy Affeldt gave back a run in the eighth, and Sergio Romo gave up a two-out, two-run homer in the ninth. Javier Lopez entered and got Jason Giambi to pop out to end the night.

"That's a typical Coors Field game," Bochy said, "but we held on."