PHOENIX -- August is over and the Arizona Diamondbacks, of all teams, have a six-game lead in the NL West.
Miguel Montero hit a three-run homer for the second straight game and the Diamondbacks -- the last-place team in the division the past two seasons -- won their ninth in a row by beating the Colorado Rockies 4-2 on Wednesday night.
"We've been playing good, man," Montero said. "It doesn't matter who we're playing."
Josh Collmenter (9-8) limited the Rockies to two runs in six innings as the Diamondbacks set a franchise record with 12 consecutive home wins. The nine-game overall streak is Arizona's longest since a franchise-best 12 in a row from June 18-30, 2003.
"The energy level is really good right now," Diamondbacks manager Kirk Gibson said. "We play really good at home, really good."
The Diamondbacks' starting pitchers have a 1.05 ERA during the winning streak, allowing seven earned runs in 60 innings.
"I think there's probably maybe just a little bit of internal competition," Collmenter said. "No one wants to be the guy that messes it up. We want to keep it going."
Sean Burroughs had a pinch-hit RBI single for the Diamondbacks, who maintained a six-game lead over second-place San Francisco in the NL West. The Giants beat the Chicago Cubs 4-0 earlier in the day. Arizona opens a three-game series in San Francisco on Friday night.
"We're ready," Gibson said. "We don't expect it to be easy. We'll play hard whether we win three, one, two, whether we get swept. We're going to go play hard and we'll pick up the pieces if the results aren't good."
Dexter Fowler, without a home run all season before this series, hit a solo shot for the second night in a row for Colorado.
The rookie Collmenter, 3-1 in his last five starts, allowed five hits, struck out three, walked none and hit a batter. Four Arizona relievers blanked Colorado for the last three innings, capped by J.J. Putz in the ninth for his 35th save in 39 tries.
"They are swinging the bats well and their pitchers are making their pitches," Fowler said. "Put all that together, you got a good team. We had some opportunities and didn't capitalize on them and came out on the bottom."
The Rockies, swept for the fifth time this season, have lost five of six. Esmil Rogers (6-4) gave up four runs on seven hits in six innings to drop to 0-3 in his last four starts.
"Once again tonight we got eight hits, we scored two runs," Colorado manager Jim Tracy said. "Last night we got 13 hits, we scored four runs. There were people out there to be knocked in we just couldn't do it. They took one swing in the first inning as our starter was trying to settle in and it is the difference in the game."
Arizona had two runners thrown out at home and Colorado one.
Seth Smith doubled with two outs, then scored on Eliezer Alfonzo's single in the Rockies' second. The catcher Montero threw out Alfonzo trying to take second on the play, ending the inning. Fowler's two-out homer, on a 1-2 pitch from Collmenter, cut Arizona's lead to 3-2 in the third.
Aaron Hill, who saved a run with a diving stop in the fourth, doubled with two outs for Arizona in the sixth, then Parra was walked intentionally. Burroughs, pinch hitting for Collmenter, singled up the middle off Rogers' glove to bring in Hill and make it 4-2.
Ryan Roberts tried to score from first on Montero's double to left in the seventh, but the left fielder Smith threw the cutoff to second baseman Mark Ellis. The catcher Alfonzo took the relay throw and made the tag for the out. Parra was easily thrown out trying to score after an errant throw to third in the eighth.
Upton was hit by a pitch for the 16th time, tied with Washington's Danny Espinosa for most in the NL. ... Parra's nine outfield assists this season are a career high. ... Manager Jim Tracy says SS Troy Tulowitzki was out of the lineup because of a sore left wrist, not because he was hitting .115 (6 for 52) against Arizona this season. He struck out as a pinch hitter to end the game. ... Montero's 72 RBIs are second only to Upton (80) for Arizona. ... The Diamondbacks send Joe Saunders (9-11) against the Giants' Matt Cain (10-9) in Friday night's series opener. ... The Rockies don't play Thursday, then open a weekend series at San Diego on Friday. Colorado's Kevin Millwood (1-1) faces the Padres' Aaron Harang (12-4).