DENVER -- The Arizona Diamondbacks have gone on a timely winning streak and done it without looking back. They regularly take an early lead, hold it and haven't had to endure any stressful comebacks.

It was that way again Saturday night when the Diamondbacks beat the Colorado Rockies 6-2, assuring they would win the key weekend series. The Diamondbacks have a 5 1/2-game lead over the Rockies for the top National League wild card spot with a chance to sweep the series Sunday. Arizona last won nine consecutive games from Aug. 23-31, 2011.

"September baseball's pretty special," Diamondbacks manager Torey Lovullo said. "When you start to play as good as we are, something special can happen."

J.D. Martinez hit a three-run homer with two outs in the first and singled home a run with two outs in the ninth when the Diamondbacks scored a second run on a wild pitch, the second time in the game that happened.

The Diamondbacks have scored at least one run in the first inning in five consecutive games, their second-longest streak of the season. They have scored two or more first-inning runs in four of the past five contests.

Arizona has held the lead for 52 consecutive innings. It is the third-longest streak since 1920 when the live-ball era began. The 1963 St. Louis Cardinals had a 53-inning streak, and the 1983 Baltimore Orioles held the lead for 55 consecutive innings. The last time the Diamondbacks trailed was after the second inning Aug. 25, when they were behind the San Francisco Giants 1-0.

"We talked about playing downhill baseball from Day 1 here, and our guys are ready to play in the first inning, and that's what it tells me," Lovullo said. "We're executing, we are doing the things we are supposed to do to score runs, and then the pitchers deserve as much credit as anybody because they're going ahead and executing shutdown innings."

Colorado remained 1 1/2 games ahead of Milwaukee for the second wild card. The Rockies have lost three straight and nine of their past 13 games. In those 13 contests, they have scored two or fewer runs four times and three or fewer runs eight times. After going 1-for-13 with runners in scoring position Friday, the Rockies went 0-for-7 in such situations Saturday while being held to four hits.

"We're not hitting well enough to break through," Rockies manager Bud Black said. "We had a couple of chances to get a hit to get closer -- didn't happen."

Diamondbacks starter Patrick Corbin (13-11) left after issuing a one-out walk to DJ LeMahieu in the sixth when the Rockies scored an unearned run without benefit of a hit. Right fielder Martinez misplayed Nolan Arenado's line drive for a two-base error. Mark Reynolds' ground out netted a run to make it 4-2, but J.J. Hoover stranded a runner at third when Ian Desmond took a third strike.

Corbin gave up two hits and two runs (one earned) in 5 1/3 innings with three walks and four strikeouts in his 96-pitch outing. In his past five starts (35 2/3 innings), Corbin is 5-0 with a 0.50 ERA, eight walks and 33 strikeouts.

"It wasn't the length that he's been giving us," Lovullo said. "It's hard to pitch at this altitude. But Patrick pitched into the sixth inning and turned it over to the bullpen. But I thought he kept a very right-handed hitting offensive lineup in check that does very well against left-handed pitching."

David Hernandez gave up two two-out singles in the seventh, but left-hander Andrew Chafin came on and struck out Charlie Blackmon.

The Diamondbacks scored an unearned run in the sixth without hitting the ball out of the infield and took a 4-1 lead. With one out, Arizona loaded the bases on an infield single, walk and third baseman Arenado's error on Corbin's sacrifice. Chris Rusin fielded Daniel Peralta's hard one-hopper and got the forceout at home only to then throw a wild pitch that brought in a run.

Martinez's homer came with two outs in the first. He connected on Gray's flat 2-2 slider and drove it an estimated 449 feet over the wall in center for his 14th home run with the Diamondbacks and 30th overall this season. The homer ended Gray's string of 18 2/3 innings without allowing a home run.

Gray (6-4) gave up five hits and the three first-inning runs in five frames. He threw 100 pitches with a season high-tying three walks and six strikeouts.

Before going on their nine-game winning streak, the Diamondbacks lost 12 of 18 games, a tailspin they have put in the distant past with their late-season surge.

"We were having some tough moments," Lovullo said. "It was probably three or four weeks of baseball that we weren't getting some timely hitting or we were just finding a way to not do enough to win some games. To me that's to be expected.

"We stayed with the process. We stayed with what we did every single day when it was working. We didn't change. We didn't panic. And it's a credit to these guys they came out the other end. I knew it would happen."

NOTES: Arizona RHP Jimmie Sherfy, 25, was recalled from Triple-A Reno where he went 2-1 with 20 saves and a 3.12 ERA in 44 games and began his second stint with Arizona this season. ... Rockies RHP Chad Bettis will start Monday against San Francisco with RHPs Tyler Chatwood, Antonio Senzatela and LHP Chris Rusin scheduled to pitch Tuesday against the Giants in an order to be determined. ... Rockies 2B DJ LeMahieu played in his 800th career game and extended his hitting streak to 10 games.