Denver, CO – Joe Saunders pitched six quality innings and ahead run in the sixth inning, as the NL West-leading 3, in the rubber match of a three-game set.
"I think we left at six games and we're coming back at seven, so we're making progress," Arizona manager Kirk Gibson said. "None of them are easy. We're getting closer to the initial finish line."
Saunders (10-12) was nearly pulled after putting the first two hitters on in the sixth, but manager Kirk Gibson stuck with the veteran holding a 4-3 lead. The left-hander set down the next three hitters to get out of the jam, ending his three-run, seven-hit outing.
Kevin Millwood (2-2) was one of three Rockies to hit solo home runs, but the starter yielded four runs on 10 hits in 5 2/3 innings to take the loss, the club's third in four games.
Arizona pulled ahead with two runs in the sixth. Paul Goldschmidt singled leading off the frame and scored the tying run on John McDonald's two-out double to left. Saunders then slapped a base hit down the left-field line to bring in McDonald with the deciding run.
Upton added insurance with his 28th home run of the season in the seventh.
Arizona's bullpen rebounded from squandering a 3-1 lead on Tuesday. Bryan Shaw and Alberto Castillo combined for a scoreless seventh, and David Hernandez, who was touched for five runs just 24 hours earlier, hurled a 1-2-3 eighth.
J.J. Putz closed it out in the ninth en route to his 37th save of the year.
"They've been doing it all year. That's why they have 82 wins right now," Rockies manager Jim Tracy said of Arizona's clutch play.
The Diamondbacks jumped in front on Montero's blast in the third frame, a two- run shot after Aaron Hill was thrown out at third trying to advance on Upton's single.
Millwood led off the bottom half with his third career round-tripper, and Carlos Gonzalez crushed a no-doubter into the second deck in right-center three batters later.
Colorado's Wilin Rosario sent one an estimated 448 feet into the left-field stands for his first career home run in the fourth.
Saunders eclipsed his nine-win total of a year ago, when he split the season with the Angels and Diamondbacks...Montero extended his hitting streak to a career-high 15 games...Arizona won despite stranding 12 runners...Rockies reliever Jim Miller recorded the final two outs in the ninth in his first big- league appearance since September 20, 2008...Arizona won the season series, 13-5.