DENVER -- Traveling to the Mile-High City did nothing to cool off the Arizona Diamondbacks.

The torrid Diamondbacks extended their winning streak to a season-best eight games Friday night as they started their key series against the Colorado Rockies with a 9-5 win.

The victory widened the distance between the teams in the National League wild-card race.

The Diamondbacks broke open a close game with a five-run seventh that was highlighted by a pinch-hit three-run homer by Daniel Descalso, who spent the previous two seasons with Colorado.

"He has an incredible heartbeat," Diamondbacks manager Torey Lovullo said. "He doesn't get intimidated by the moment, and there's nothing too stressful for him that he can't handle. It's a credit to him for being able to slow the game down and execute."

Arizona moved 4 1/2 games ahead of the Rockies in the race for the top NL wild-card spot. The Rockies, who have lost eight of 12 and 13 of their 20 past games, lead the Milwaukee Brewers by just 1 1/2 games in the chase for the second wild card.

Diamondbacks starter Taijuan Walker (8-7) allowed three hits in five scoreless innings with three walks and 10 strikeouts. He became the third pitcher in franchise history to not yield a run in an outing that lasted five or fewer innings and have at least 10 strikeouts.

In his past three starts, Walker is 2-0 with an 0.54 ERA. He threw 93 pitches, 31 in the first when he issued two walks, loaded the bases but struck out Carlos Gonzalez on a curveball to end the inning. Walker said he wasn't aware he recorded his first eight outs on strikeouts, the first time that has been done in the history of Coors Field.

"We were just going out there and being aggressive with the fastball again, getting ahead," Walker said. "Getting strike one and strike two. My pitch count got up there a little bit, a couple walks in that first inning which I didn't like. But just stayed aggressive, kept attacking them"

Three errors by the Rockies, two on the same play, jump-started the Diamondbacks' big seventh that gave Arizona a 9-2 lead. With one out, A.J. Pollock walked, stole second and took third on catcher Jonathan Lucroy's throwing error. Adam Ottavino fell behind Paul Goldschmidt and intentionally walked him. Ottavino then made a low pickoff throw to first. Pollock scored, and Goldschmidt took second on first baseman Mark Reynolds' wide throw home.

Jake Lamb singled home a run before Descalso jumped on Mike Dunn's 0-2 slider and hit his fifth career pinch-hit home run and second this season, connecting on the third pitch and third slider Dunn threw.

"(I was) trying not to swing at another ball in the dirt," Descalso said, "so I was looking for some mistake out over the plate and just trying to get a pitch to hit there. He hung a slider and I was able to put a good swing on it.

After Walker left, the Rockies finally broke through in the sixth. Ian Desmond led off with a single and scored when Gonzalez doubled. He moved up on a ground out and scored to cut Arizona's lead to 4-2 on Trevor Story's sacrifice fly.

The Rockies stranded 12 runners and went 1-for-3 with runners in scoring position. They were 0-for-11 in such situations before Story doubled home two runs with two outs in the seventh after the Rockies loaded the bases with no outs and scored on Gonzalez's grounder.

Rockies starter Kyle Freeland (11-9) gave up five hits and three runs in four innings and is winless in his past five starts. He wasn't particularly efficient, throwing 44 of 74 pitches for strikes.

"Kyle was a little off with all his pitches," Rockies manager Bud Black said. "His fastball command was not quite there, and his slider was not as good as we have seen it. It was hard for him."

Arizona scored once in each of the first three innings.

Pollock singled home a run in the first after Freeland began the game with consecutive walks.

The Diamondbacks scored in the second on Walker's infield single. Reynolds wasn't near the base when he fielded Walker's grounder. Freeland didn't break off the mound, leaving Reynolds to dash to first.

Martinez hit a sacrifice fly in the third inning, scoring Pollock, who had tripled.

The Diamondbacks employed an unusual -- and successful -- outfield alignment against DJ LeMahieu, who went 1-for-5 and stranded three runners. He hits the ball to right field most of the time, so the Diamondbacks stationed their left fielder behind second base, their center fielder in right-center and their right fielder near the foul line, leaving left field vacant. Lovullo said first base coach Dave McKay suggested the shift in a pre-game meeting.

"It's a super shift times ten, never seen anything like it...," Lovullo said. "We just wanted to take away the dominant lanes. We were taking some risks. We felt like we won the moment, and we were able to collect the outs that we were supposed to."

NOTES: The Rockies recalled RHPs Carlos Estevez, Jeff Hoffman, LHP Zac Rosscup, C Tom Murphy, IF Ryan McMahon and OF Mike Tauchman from Triple-A Albuquerque. OF Raimel Tapia will be recalled Tuesday, the day after Albuquerque's season ends. ... The Diamondbacks recalled RHPs Silvino Bracho, J.J. Hoover and C John Ryan Murphy from Triple-A Reno and selected the contract of IF/OF Kristopher Negron from Reno. ... Diamondbacks RHP Rubby De La Rosa, who underwent his second Tommy John surgery Aug. 21, was released. ... Rockies LHP Tyler Anderson (left knee surgery) will make his third and final rehab appearance for Triple-A Albuquerque on Sunday or Monday before rejoining the Rockies.