PHOENIX -- A sellout crowd showed up for Opening Day at Chase Field expecting to see a pitchers' duel.

Instead, a game of Home Run Derby broke out between the National League West rivals.

Pitchers' duel or home-run hitting contest, the D-backs were just happy they came out on the winning end of the 9-8 decision on Monday.

"Heck of a game," Arizona manager Bob Melvin said.

The D-backs' offensive production was not only impressive, it was historic.

Felipe Lopez, making his debut in Sedona Red, and veteran Tony Clark each homered twice and both switch-hitters hit them from each side of the plate. It was the first time two teammates had ever done it on Opening Day and it was the first time in the regular season since New York's Jorge Posada and Bernie Williams on April 23, 2000.

"That's quite a debut," Melvin said of Lopez, who was signed in December to replace Orlando Hudson at second. "I know it makes him that much more comfortable being able to contribute like that right away."

Lopez hit both home runs to the opposite field.

"It's nice, but to me it was most important to get the win," Lopez said. "I'm just glad we ended up fighting back."

The two teams went back and forth throughout the game, combining for 22 hits, eight homers and 11 pitchers used.

Colorado jumped on top, 4-2, with a four-run third inning off Arizona ace Brandon Webb, who did not appear to be on top of his game while lasting just four innings and allowing six runs.

The D-backs, though, bounced right back with four runs of their own in the bottom half of the third with Clark's two-run homer off Colorado ace Aaron Cook capping the frame and sending the right-hander to the showers.

"You're talking about two of the best sinkerballers in the game," Melvin said. "They just didn't have their best stuff today."

The back and forth continued over the next several innings. The Rockies scored two in the fourth and the D-backs answered with one to go back on top, 7-6.

The two teams traded runs in the fifth, and after a scoreless sixth, they did so again in the seventh with the D-backs going back ahead, 9-8.

"It was like a heavyweight fight," D-backs third baseman Chad Tracy said. "Every time we scored, they scored."

If it was a fight, then it was Tracy who delivered the knockout blow when he homered for the final run off Jason Grilli in the seventh.

For Tracy, who pulled his hands in to hit a slider breaking in over the right-field wall, it was a continuation of a hot spring at the plate and was more evidence that his right knee is healthy after more than two years of giving him problems.

"We'll see how things play out," Tracy said. "This is just one of 162, so we'll see."

The D-backs like what they've seen of Lopez this spring.

"I think Felipe set the tone," Clark said. "Hitting is contagious and so is not hitting. That's why Felipe's ball was so important. It allowed guys to relax a little bit, the shutout was gone, the no-hitter was gone and we were ahead. It makes a difference. By getting us on the board quickly, it gave us a chance to take a deep breath. They kept throwing punches and we were fortunate enough to push back."

Lopez does have power. The 28-year-old leadoff man hit 23 of them in 2005 for the Reds, but he has downplayed that part of his game this spring.

"It's there, but I'm not looking to hit home runs," he said. "If it happens, it happens. My job is to get on base at the top of the order."

Clark's performance made Melvin look awfully smart. The skipper elected to play Clark at first and move Tracy to third in place of Mark Reynolds, while also inserting Eric Byrnes into the lineup in right in place of Justin Upton. Byrnes did not get a hit, but he did drive home a run with a sacrifice fly.

"The players played well," Melvin said, deflecting any credit.

While the story of the game was the offense, several relievers pitched well for the D-backs.

Most important was the 1 1/3 innings setup man Tony Pena threw to get the D-backs through the seventh and eighth innings.

Chad Qualls, who is in his first full year as the club's closer, then came in to retire the Rockies in order in the ninth.

"Just nice to get the first appearance whether it's a save situation or not," Qualls said. "I had the butterflies during batting practice, so to be able to go out there on Opening Day and get your first outing out of the way and have it be a one-run save, it's great to just go out there and get the job done."