SAN FRANCISCO -- The Colorado Rockies stood at the dugout rail and watched their division rival celebrate a third World Series championship in five years. Giants October ace Madison Bumgarner even mounted a horse to carry the flag around the outfield warning track.

None of the fanfare seemed to faze Rockies rookie Eddie Bulter, who made quite an impression of his own to help spoil San Francisco's home opener in a 2-0 victory Monday before a raucous sellout crowd.

Butler outdueled fellow rookie Chris Heston and shut down the Giants over 5 1/3 innings, helping Colorado match its best road start at 4-0 that was also done in 2006.

"The confidence has been there this year," said Butler, greeted in the clubhouse with a high-five from catcher Nick Hundley. "I'm just trying to give the team a chance. Giving up a run or two is no big deal. This team is able to score runs for me. The bullpen has been picking me up."

Troy Tulowitzki, back in the lineup after a day off, had the only RBI of the game with a run-scoring single in the fourth against Heston (1-1).

Facing the Giants for the first time, Butler (1-0) allowed five hits, walked six and struck out one. Colorado's 2012 first-round pick worked out of bases-loaded jams in the first and second innings.

The Giants were shut out in a home opener for only the third time in the San Francisco era and first since home run king Barry Bonds' final season of 2007.

"You hate to lose your opener," Giants manager Bruce Bochy said. "A big day with the ceremonies. ... We just couldn't get a timely hit."

Fourth Rockies reliever Rafael Betancourt struck out two in a perfect ninth for his first save since Aug. 20, 2013. Colorado matched its best road start at 4-0, also done in 2006.

"This is a tough place to hit and it's a tough place to play defense, but we've had some success here the last couple of years," Rockies second baseman by DJ LeMahieu said. "Besides the wind and the sun, it's the fans who make a huge impact. There is a lot of emotion that comes out."

Just the second rookie in San Francisco history to start a home opener, Heston allowed one earned run, struck out five and walked two over seven strong innings. His parents were in the stands among the 42,019 fans at sold-out AT&T Park for the occasion.

In the seventh, Giants shortstop Brandon Crawford saved a run when he stopped a hard grounder for a single by LeMahieu. Hundley doubled with two outs but had to hold up at third.

But Hundley wound up scoring anyway moments later on a pitch that got away from Heston. Hundley's slide was short of the plate but he reached in with his left hand and the ball came loose from Heston's glove. It ended up under Hundley's leg in a crazy sequence.

"I think when I went to tag him he just kind of kept sliding and kind of rolled into my glove and rolled the ball out," Heston said. "It was a little unfortunate. It happens."

Bochy challenged but the call was upheld in 1 minute, 22 seconds. Heston received an error on the play.

"I've got nothing to lose there," he said.

Bumgarner -- who will be honored again Tuesday -- cleared the horse riding with Bochy beforehand. Cain and other members of all three World Series champion teams hoisted the flag: Tim Lincecum, Jeremy Affeldt, Sergio Romo, Santiago Casilla and Javier Lopez. Catcher Buster Posey was in the bullpen warming Heston.

"I could probably say I'll probably never get a chance to do that again," Bumgarner said. "I don't know if anybody's ever done that before or not. It was pretty interesting and it was fun to do in front of fans here at home."

TRAINER'S ROOM

Rockies: Closer LaTroy Hawkins is getting a "breather," as manager Walt Weiss put it in announcing the RHP will move out of the ninth-inning role for now after a blown save Sunday.

Giants: RHP Erik Cordier was scheduled to throw to hitters as he works back from a strained right forearm. ... RF Hunter Pence (broken left forearm) was to be reevaluated by the team's medical staff, while 3B Casey McGehee (left knee strain) was considered day to day.

UP NEXT

Rockies: RHP Christian Bergman (1-0) makes his first start of the season after earning a victory in the Rockies' home opener Friday against the Cubs.

Giants: RHP Tim Hudson (0-0) makes his home debut looking to improve to 6-2 lifetime against the Rockies. He didn't have a decision against them in four 2014 starts.