O'Reilly scored 13:47 into the third and Colorado extended its winning streak to three with a 3-2 victory over Montreal on Thursday night.
An 18-year-old chosen 33rd overall by the Avalanche in the 2009 draft, O'Reilly got his own rebound and put a shot past Carey Price for his first goal in seven games, a scenario O'Reilly never could have foreseen when he was last in the arena in June.
"No, I never thought I'd be here this far, at least," said O'Reilly, who plans to give the milestone puck to his grandmother. "It's pretty amazing. You never know when it's going to happen and finally it does and you're like, 'Wow!' This is what you dream about forever. And after I scored I was like, 'What do I do now?' I didn't know what to do, how to celebrate or anything, I was feeling so good."
Craig Anderson stopped 29 shots, including a furious flurry by Montreal in the dying seconds.
"It was exciting," Anderson said. "The fans were excited, I was excited -- I got a lucky break. I think I made one save that was kind of a scramble in front, it went to their guy and he kind of shoveled it to the net and it hit my toe and went right back to him. He had a wide open net and chipped it over my leg and I wonder how he missed the net. We've just got a little luck on our side right now and we'll take it. We got two points and let's get out of here."
Milan Hejduk and Kyle Cumiskey also scored for the Avalanche (4-1-1), who are five games into a seven-game trip, Colorado's longest of the season.
"We're a pretty resilient group right now," Avalanche coach Joe Sacco said. "We knew they were going to come out with lots of energy. Unfortunately we had some penalties and they started to get some chances but we responded very well in the second period. We came out and that may be one of the best periods we've had all season, and it's just good to see our guys respond like that. We battled hard and we've got good compete in our game."
Roman Hamrlik and Tomas Plekanec scored for the Canadiens, who have lost four straight since opening the season with a pair of overtime wins.
Plekanec drew Montreal even at 2 when he took Andrei Kostitsyn's centering pass and put a shot through Anderson's pads 8:26 into the third.
The Canadiens, who celebrated their 100th season last year, did not play any games in 2004-05, when the league's schedule was ultimately canceled because of a work stoppage.
Price, who faced the Avalanche for the first time, stopped 20 shots. He debuted a new mask featuring six "Ace of Spades" cards, yet he was decidedly unlucky in the second.
Cumiskey got credit for his first goal since January 2007 as Colorado banked in two shots off Montreal defensemen in the second period to take a 2-1 lead.
"We were back on our heels in the second period and they were taking it to us and that's what happens," Canadiens right wing Brian Gionta said. "It doesn't matter what the breaks are, we let up in that second and that's what caused it."
Hejduk drew the Avalanche even at 1 during 4-on-4 play 13:39 into the middle period. He got credit for his second goal of the season 10 seconds after Plekanec was sent off for cross-checking when his shot struck Josh Gorges' left skate, sending the puck skidding slowly between Price's pads and into the net.
Price had little chance on Colorado's second goal at 19:32. Cumiskey's shot from the left side struck Shawn Belle, who was called up from Hamilton of the AHL on Tuesday, and caromed past Price to give the Avalanche a 2-1 lead with 28 seconds left in the second.
"Two lucky bounces but they stuck to their game plan, which was throwing pucks to the net, and we kind of got away from ours in the second period," Belle said.
Hamrlik scored his second goal of the season on a power play midway through the first. Canadiens forwards Kostitsyn and Plekanec exchanged the puck in the right corner and Plekanec moved up to feed a centering pass to Hamrlik in the slot, who put a shot along the ice into the open left side.
Cumiskey, drafted 222nd overall by the Avalanche in 2005, had one goal in his previous 59 games. He scored his first and only other NHL goal on Jan. 6, 2007 against Minnesota's Manny Fernandez. ... Belle appeared in nine games with Minnesota in 2006-07. ... The Canadiens are 56-27-16-1 overall in home openers, including two wins and six losses during their first eight seasons in the National Hockey Association before they joined the NHL in 1917-18 as one of the league's founding franchises. ... Montreal went 24-10-7 last season at the Bell Centre.
Copyright by STATS LLC and The Associated Press
Arena: Bell Centre Location: Montreal, Quebec
Referees: Dave Jackson, Marc Joannette Linesmen: Pierre Champoux, Brad Kovachik
Attendance: 21,273 (100.0% full)
Team Stat Comparison
Power Play Goals
Power Play Opportunities
Shots on Goal
Roman Hamrlik (2)
(Power Play) Assists: Tomas Plekanec, Andrei Kostitsyn
Milan Hejduk (3)
Assists: Kyle Cumiskey, Paul Stastny
Kyle Cumiskey (1)
Assist: Craig Anderson
Tomas Plekanec (2)
Assist: Andrei Kostitsyn
Ryan O'Reilly (1)
Assists: David Jones, Cody McLeod