DENVER — The Colorado Rockies are roaring into the World Series like no team before them.

More momentum. More rest, too.

With their 21st win in 22 games, the relentless Rockies beat the rattled Arizona Diamondbacks, 6-4, in Game 4 last night to sweep the NL championship series at chilly Coors Field.

Series MVP Matt Holliday hit a three-run homer into the pine-filled rock pile in center field that capped a six-run outburst in the fourth inning, and Colorado was on its way.

Born as an expansion team in 1993, the wild-card Rockies are headed to their first World Series.

"They always say baseball is about confidence and we have a lot right now," outfielder Brad Hawpe said.

The Rockies have a record eight days off before opening the World Series at either Cleveland or Boston on Oct. 24. The Indians lead the ALCS, 2-1.

"It was fun, this has been a great ride. We're not done yet," said Rockies first baseman Todd Helton, the face of the franchise who cradled the last out in his glove. "We're going to keep it going."

With their delirious fans waving brooms and towels, the Rockies joined the 1976 Big Red Machine as the only teams to start a postseason with seven straight wins. Colorado has won 10 in a row overall and lost only once since Sept. 16.

"It's unbelievable. I never dreamed I'd have this opportunity," Holliday said. "With this group of guys I'm so excited to be a part of it. This MVP award goes 24 other directions."

Just one strike from postseason elimination on the final weekend of the season, the Rockies have become a charmed team that seemingly cannot lose.

"This has been different. They're very, very unselfish, and they kept working together, working together and believing," Rockies manager Clint Hurdle said.

Colorado had never won more than 83 games before going 90-73 this season and sneaking into the playoffs with a 9-8, 13-inning win over San Diego in the wild-card tiebreaker — rallying for three runs against career saves leader Trevor Hoffman.

After sweeping Philadelphia in the first round of the playoffs, the Rockies routed a D'Backs club that led the league with 90 victories.

"Once the sting of this subsides, we'll be able to reflect that we did have a great year," Arizona manager Bob Melvin said.

Ahead 6-1, the Rockies withstood Chris Snyder's three-run homer in the eighth. Chris Young doubled with one out in the ninth off closer Manny Corpas, but Stephen Drew popped out on a 3-0 pitch.

"If that's not the tying run, then I obviously don't let him swing," Melvin said. "But right there you know you're going to get a fastball, you know you're going to get a pitch to drive. He just came off it a hair and popped it up."

Eric Byrnes followed with a checked-swing grounder that shortstop Troy Tulowitzki charged. His throw beat Byrnes' headfirst dive, and Helton threw his arms in the air.

The Rockies are the first team since the 1935 Chicago Cubs to win at least 21 of 22 after Sept. 1, according to Elias Sports Bureau.

"There comes a point in time when a team is no longer hot, they're simply good," Arizona's Tony Clark said. "And I think that's what we saw with Colorado."

Before this season, the Rockies had just one postseason victory, back in 1995, when they were eliminated by Atlanta in the first round.

With the Rockies trailing 1-0 with two outs in the fourth and runners at second and third, Hurdle pulled his starting pitcher, rookie Franklin Morales, for a pinch-hitter.

He sent up rookie Seth Smith, who had only eight career at-bats when he was placed on the playoff roster.

Smith fell behind 0-2 in the count against rookie Micah Owings, then blooped a 1-2 pitch into left field.

The Rockies caught another break when Arizona first baseman Conor Jackson couldn't catch Willy Taveras' easy grounder. The error set up Kaz Matsui's run-scoring single.

Holliday sent the sellout crowd of 50,213 into a frenzy when he drove Owings' slider over the center-field wall to make it 6-1.