Updated

New coach Patrick Roy and the Colorado Avalanche got a key third-period goal on the road to stay unbeaten on the season.

P.A. Parenteau scored early in the third period to help the Avs edge Toronto 2-1 on Tuesday night.

Cory Sarich also scored for Colorado (3-0-0), which got another terrific start from Semyon Varlamov in net. The 25-year-old Russian has stopped 88 of 91 shots in three games.

Tied 1-1 going into the third, Colorado went ahead at 2:30 on a two-on-one with Jamie McGinn setting up Parenteau.

The good stood up to video review.

"According to Rule 78.4 'if an attacking player has the puck deflect into the net, off his skate or body, in any manner, the goal shall be allowed.' Good goal Colorado."

Avs rookie Nathan MacKinnon, the 18-year-old first overall pick in the draft, got an assist — his fourth of the season — on Parenteau's third goal of the season.

"It was a great team effort, great team effort," Roy said.

Joffrey Lupul scored for Toronto (3-1-0), which charged hard during a power play midway through the third period but was unable to score.

"That was a big (penalty) kill for us," Roy said. "Guys were there for a long time, and then they sacrificed their body."

Jay McClement's absence due to his wife going into labor left a Leafs lineup already missing Mark Fraser, Nikolai Kulemin and Frazer McLaren because of injury and David Clarkson because of suspension without another key player. McClement's wife gave birth to a baby boy.

"You're going to have to deal with adversity throughout the course of the season," Toronto coach Randy Carlyle said. "And injuries and birth of children, family illness — all those things roll into the things that you have to deal with. We're no different than anybody else."

Said Leafs captain Dion Phaneuf: "We gave up too many chances. Bernie (Bernier) kept us in it. It was right there for us."

Colorado, playing an up-tempo exciting brand of hockey under Roy, outshot Toronto 33-28 including 15-7 in the second period.

MacKinnon has collected a point in each of his games including two assists in his NHL debut Oct. 2 — at the age of 18 years 31 days. That made him the youngest NHL player to collect two points in a game since Jan. 8, 1944, when Ted Kennedy had four points for the Leafs at the age of 18 years 27 days.

Jonathan Bernier got the start in goal for Toronto after stopping 46 of 47 shots in one start and a relief appearance.

Toronto went ahead at 13:12 of the second period when Lupul stuffed the puck past Varlamov on a scramble that ensued after a Colorado giveaway. The Avs goalie was down and seemingly had the puck underneath him, but did not get a whistle and the Leafs jammed it during the ensuing melee.

Lupul, scoring his second of the season, helped his own cause by bodying MacKinnon in the corner as he tried to clear the puck. Carter Ashton got an assist for his first NHL point.

The Avs solved Bernier at 16:39 of the second when Sarich beat him from an acute angle high to the short side. The Leafs goalie seemed to be expecting a pass rather than a shot.

"He made a good shot, but that's definitely a save that I've got to make and it's a routine save," Bernier said. "That's a goal that I want to take back."

"He's given us a chance to win every time he's been in there. And been spectacular at some points," Lupul said. "We can't ask anything more of him."

NOTES: Dave Bolland wore the 'A' in McClement's absence. McClement played 104 games for Colorado over the 2010-11 and 2011-2012 seasons. ... Toronto's next game is Thursday in Nashville ... The ACC crowd serenaded Walter Gretzky, who was at the game for his 75th birthday, with "Happy Birthday."