Then it all fell apart in a hurry.
Colorado wasted a terrific start by Jhoulys Chacin when Milwaukee scored three times in the eighth inning, and the Brewers went on to a 5-4 victory in 10 innings on Monday.
"We battled the whole game," Gonzalez said. "That happens sometimes. There has to be a loser. But if we play that way for a lot of games, we're going to be fine. We're going to have better results."
Rickie Weeks sparked the winning rally when he stole second after he was hit by a pitch with one out. Adam Ottavino (0-1) then issued an intentional walk to Ryan Braun and lost Aramis Ramirez to another walk before Jonathan Lucroy ended the game with a fly ball to center field.
"The thing that hurt was the hit batter," Ottavino said. "I had him 0-1 and tried to come inside. I just nicked his foot and it started all the trouble."
Weiss got a one-year deal when he was hired in November after Jim Tracy stepped down following a franchise-worst 64-98 season. Before moving into the dugout with the Rockies, his only head coaching experience was one year at Regis Jesuit High School in Aurora, Colo.
And it was quite the opener for the 1988 AL Rookie of the Year with Oakland.
"It's a little different 'cause you've got to think ahead of course a lot more than you do as a player," Weiss said. "As a player you're not really going through all the 'What ifs' in your mind as you do as a manager. But, you know, I felt good about the way our guys played."
Chacin pitched 6 2-3 innings of one-run ball and the Rockies carried a 3-1 lead into the eighth inning. But their bullpen was unable to hold on.
Braun drove in a run with an infield single to shortstop before Ramirez sent a 2-2 pitch from Wilton Lopez into the left-field corner, picking up right where he left off last season when he led the National League with 50 doubles.
Norichika Aoki trotted home from third and Braun came all the way around from first, raising his right arm in celebration as he crossed the plate with the go-ahead run.
"I was hoping a cloud would come through," said Ramirez, who had to deal with some shadows on the field before his key hit. "I got lucky."
John Axford then came in for the Brewers on his 30th birthday and yielded a first-pitch homer to Dexter Fowler after he struck out the first two batters in the ninth. Axford, who blew nine save opportunities a year ago, was booed as he trudged off the mound after striking out Josh Rutledge to end the inning.
Fowler finished with three hits, and Tulowitzki and Gonzalez each had two.
"We've got the ability to get quick points," Weiss said. "We have some guys that hit the long ball today. We've got guys in the lineup that can strike quick."
It was Milwaukee's first win in the opener since it beat the Chicago Cubs 4-3 in 10 innings at Wrigley Field on March 31, 2008. The Brewers hadn't won a home game on opening day for six years, providing a compelling reason for the thousands of fans who tailgated for hours before Monday's first pitch to continue celebrating Lucroy's well-placed fly ball when they returned to the parking lots around the ballpark.
Jim Henderson (1-0) worked a perfect 10th for the victory and Aoki also had a solo homer for Milwaukee, which is hoping to make it back to the playoffs after finishing strong last season. Yovani Gallardo allowed 10 hits in his fourth consecutive opening day start, but limited the damage by holding the Rockies to three runs in five innings.
"He was in trouble every inning, still only gave up three runs," Brewers manager Ron Roenicke said. "I think when you don't have your good stuff and keep your team in the ballgame like he did, even though offensively we didn't do much there until the eighth inning that shows you know how to get out of trouble."
Gonzalez led off the third with a single into right field and Tulowitzki drove the next pitch over the wall in right-center for his first homer since he connected against Houston on May 28. The two-time All-Star played in just 47 games last season due to a groin injury that eventually required surgery to remove scar tissue.
Gonzalez connected in the fifth, leading off with a drive to right. He made the All-Star team for the first time in 2012, but is coming off a lackluster finish at the plate—.222 in August and .262 in September and early October.
"If we play that way for a lot of games, we're going to be fine," Gonzalez said. "We're going to have better results."
NOTES: Aoki also hit his first career homer off Chacin last season, an inside-the-park liner in Milwaukee last April 20. ... Joseph Attanasio, the father of Brewers owner Mark Attanasio, performed the national anthem at the home opener for the ninth consecutive season. Asked if his dad practiced, Attanasio said: "He started singing ''O Sole Mio' on the plane ride here." ... The Rockies opened on the road for the fifth time in the past six seasons. ... It was the fifth-largest crowd in Miller Park history.
Jay Cohen can be reached at http://www.twitter.com/jcohenap