DENVER -- You couldn't convince Colorado rookie shortstop Clint Barmes that the Rockies' average age is a Major League-youngest 26 years, 324 days.

After Barmes launched an improbable two-run homer off veteran San Diego closer Trevor Hoffman to give the Rockies a 12-10, Opening Day victory, he would have sworn the figure was 20 years too high. Barmes, 25, rounded the bases with a mouth-agape, screaming smile that made him look and feel like a 4-year-old about to be hugged by a gang of 6-year-olds.

About a half-hour later, Barmes was still toddling the hallways by the clubhouse at Coors Field. Many among the sellout crowd of 47,661 had to be wondering if they were too old for such manic-depressive games during which the Rockies swung from being truly new and different to same-ol', same-ol', and back.

Barmes would take a couple of steps toward the weight room, then turn around to do media interviews. Then he'd give a heartfelt handshake to anyone who knew him. Then he'd look at the weight room, knowing he'd have a hard time getting anything done there.

"Ah, to jump into the middle of that crowd at home plate is something special, something you never want to forget, something that I can't even put into words, the feeling," said Barmes, who'd never ended a game with a homer.

It was a day for new experiences for the Rockies.

Barmes went 4-for-6 and became the first rookie to hit a game-ending home run in the history of the Rockies, who began their 13th season. He and four other members of the starting nine were playing on Major League Opening Day for the first time.

One, second-year leadoff hitter Aaron Miles, went 5-for-6, tied a club record with three doubles, and drove in the tying run. Another, Matt Holliday, had three hits, including a triple.

"It feels great to get the first win, Opening Day, get all that nostalgia and hoopla out of the way and play some baseball," said Miles, the first Colorado player to knock five hits in a game since Ronnie Belliard on May 29, 2003 against Los Angeles.

Three significant figures in the comeback had never played in a Triple-A game, much less one in the Majors:

• Jeff Baker, slated for Double-A before rookie third baseman Garrett Atkins suffered a right hamstring injury in the final exhibition game, knocked a two-run homer in the third inning. Baker also doubled with one out in the ninth off Hoffman (0-1, blown save) to start the rally with Colorado trailing, 10-8.

• Cory Sullivan, who might have gotten some Triple-A time last year if not for having to undergo Tommy John elbow ligament transfer surgery, doubled to drive in Baker and scored the tying run on Miles' single.

• Right-handed reliever Ryan Speier (1-0), the Rolaids Minor League Relief Man award winner at Double-A Tulsa, escaped a two-out, two-on situation in the top of the ninth.

"That's one of the things we're holding onto real near and dear inside that clubhouse: no matter what happens throughout the course of the season, we're not going to back down," said manager Clint Hurdle, whose team set Rockies Opening Day records for runs, hits (18) and extra-base hits (10). "We will not be intimidated.

"We'll get beat. We might get beat badly. But these guys have been ballplayers all their lives. They're not kids with skills trying to figure out how to play the game of baseball. Now we're going to have to go through some growing pains letting them play."

It seemed like familiar pain.

Colorado used a three-run homer by Preston Wilson in the first and Baker's two-run shot in the third, both off Padres starter Woody Williams, to build a 7-3 lead going into the sixth.

But Colorado starter Joe Kennedy, who had already given up back-to-back homers to Brian Giles and Phil Nevin in the second, started the sixth by giving up a single and a walk. Xavier Nady hit the first of his two homers to cut the difference to 7-6 and the Padres tied the game later in the inning.

Todd Helton's single in the bottom of the sixth tied it. But when Rockies reliever Scott Dohmann gave up consecutive solo shots to Ramon Hernandez and Nevin in the seventh, it looked like nothing had changed despite all the new faces. Colorado's bullpen had set Major League records for losses (39) and blown saves (34) in 2004, and the club finished with the second-worst record in its existence, 68-94.

Yet the Rockies didn't let that baggage or Hoffman's reputation stop them.

"Most of these guys hadn't face him before," Helton said. "To go up, not be intimidated, not think too much, go up there and hit it, they're living in the moment."

The young hitters relied on what experience they had while performing for successful minor league teams in the organization.

"It's the same game," Holliday said. "Pitchers in the Major Leagues make mistakes, also, maybe not as many as in the minor leagues. If you're able to slow it down and play it like the game that it is, I don't see any reason why we can't have the success that we've had."

Hoffman bristled at the suggestion that pitching to the Rockies is child's play.

"I don't agree with that at all," he said. "They're all wearing Major League uniforms. I don't think anybody's taking anybody for granted just because of their age."

Barmes approached the game-winning at-bat with maturity. He decided he wasn't going to swing unless he got an inside fastball. Only after swinging did he turn young again.

"I probably won't get any sleep tonight," Barmes said with the knowledge that, with the next game not until Wednesday night, missing bedtime was OK.