TORONTO -- A depleted Maple Leafs lineup was unable to keep pace with the surging Colorado Avalanche, reducing the list of NHL unbeatens by one.

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 is off to its best ever start. The Avalanche got another terrific start from Semyon Varlamov in net. The 25-year-old Russian has now 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, who may not have known too much about it as the puck deflected in off his skate past a sliding defenceman Jake Gardiner.

"Video review supported the referee's call on the ice that Jamie McGinn's shot deflected off P.A. Parenteau and entered the net in a legal fashion," the NHL said in explaining the call. "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 2013 draft, got an assist -- his fourth of the young season -- on Parenteau's third goal of the season.

"It was a great team effort, great team effort," said Avs coach Patrick Roy.

Joffrey Lupul scored for a depleted 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 labour further stripped a Leaf lineup already missing Mark Fraser, Nikolai Kulemin and Frazer McLaren through injury and David Clarkson due to suspension.

"You're going to have to deal with adversity throughout the course of the season," said Toronto head coach Randy Carlyle. "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."

While Toronto's loss column grew by one, so did the Leafs family. McClement's wife gave birth to a baby boy.

Toronto seemed off its game, reflected perhaps at the morning skate when Carlyle huddled his troops early in a bid to focus them on the task that lay ahead.

Colorado, playing an up-tempo exciting brand of hockey under Roy, outshot Toronto 33-28 including 15-7 in the second period. The Avs outhit Toronto 44-33 and won 60 per cent of faceoffs.

The game, which started as a goatending display before 19,388 at the Air Canada Centre, was the first between the two teams since October 2011 and offered Toronto fans a first NHL look at MacKinnon.

The centre from Cole Harbour, N.S., who is living with veteran goalie Jean-Sebastien Giguere and his family in Denver, is playing on the Avs' third line with McGinn and Parenteau.

He 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 registered four points for the Leafs at the age of 18 years 27 days.

MacKinnon did not look out of place, although a failed clearance from his own defensive end led to Lupul's goal.

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

Both goalies were rock-solid with Bernier continuing to impress with his positioning and rebound control. Varlamov, meanwhile, had plenty of help from his defence in clearing loose pucks.

It was a free-wheeling start to the game with few stoppages and a lot of rushes. Bernier had the crowd ooohing when he showed a quick glove hand in stopping Avs captain Gabriel Landeskog five minutes in.

Varlamov returned the favour with a little over five minutes remaining in the period, sticking out a leg to deny Lupul in full flight.

Carlyle, meanwhile, tweaked his personnel by pairing Nazem Kadri with tough guy Colton Orr and Carter Ashton on the third line. The fourth line featured Troy Bodie, Trevor Smith and Jamie Devane.

The smooth-skating first period was followed by a sloppy opening to the second. But play began to open up and Toronto went ahead at 13:12 of the second when Lupul stuffed the pack 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. Ashton got an assist for his first NHL point.

Bodie and Colorado's Cody McCleod fought after a faceoff late in the period as Maple Leaf Sports & Entertainment CEO Tim Leiweke, Bodie's father-in-law, watched from the second row behind the Leaf bench. A late flurry by Bodie had Leiweke on his feet.

The Avs finally solved Bernier at 16:39 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," lamented Bernier. "That's a goal that I want to take back."

It was the 35-year-old defenceman's 21st career goal -- and his first since Jan. 10, 2012. And it snapped a stretch of 56 saves and 110 minutes 50 seconds without a goal for Bernier.

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