DENVER — Nathan MacKinnon put on a show, slicing through Toronto’s defense with a pair of goals to give the Colorado Avalanche an early lead.

But one superstar’s brilliance couldn’t cover up the cracks elsewhere. Defensive breakdowns and a difficult night in net unraveled Colorado’s advantage, sending the Avalanche to a 6-3 loss against the Maple Leafs.

William Nylander led Toronto with five points, tying a career high with two goals and three assists. Auston Matthews added two goals and two assists, while Nicholas Paul recorded two assists. Easton Cowan and former Avalanche defenseman Nick Blankenburg also scored for the Maple Leafs. Sergei Bobrovsky stopped 30 of 33 shots, while Mackenzie Blackwood allowed five goals on 22 shots.

Toronto won the opening faceoff, and Blackwood made the first save of the night by denying Jack Roslovic on a one-timer from the slot following a setup from Matthews.

Colorado earned its first power play shortly afterward when Kirill Marchenko was called for tripping Martin Necas. The Avalanche failed to register a shot on the man advantage.

Things went from bad to worse for the visitors.

Blankenburg, who departed Colorado in free agency during the offseason, opened the scoring for Toronto. Nylander threaded a pass to the defenseman at the top of the right circle, where he fired a wrist shot over Blackwood’s glove to make it 1-0.

Colorado struggled to generate offense early, managing just one shot on goal through the opening seven minutes as the Maple Leafs controlled the momentum.

MacKinnon changed the complexion of the game with a spectacular individual effort just past the halfway point of the period. After collecting a pass from Brett Kulak, the superstar accelerated through the neutral zone and weaved past multiple defenders before slipping the puck past Bobrovsky. The goal tied the game at 1-1 and marked his fourth of the season.

He wasn’t finished.

With 4:46 remaining, MacKinnon struck again. After taking a pass from Cale Makar, he fought through the forecheck to create time and space before firing a wrist shot through traffic and past the Toronto goaltender. The goal gave Colorado a 2-1 lead.

The Avalanche had another opportunity to extend their advantage when Roslovic was called for hooking Nazem Kadri with 1:01 remaining. Colorado carried the power play into the second period.

Colorado nearly received an extended two-man advantage to open the period. With nine seconds remaining on the original power play, Troy Stecher was called for tripping MacKinnon, briefly giving the Avalanche a 5-on-3 opportunity. They couldn’t capitalize, with their best chance coming when Necas sent a one-timer over the crossbar with the left side of the net open.

The Avalanche entered the game with a perfect penalty kill, having successfully killed every penalty they had faced this season. That streak ended 6:53 into the period.

After Jaden Schwartz was penalized for high-sticking, Gavin McKenna sent a cross-ice pass to Nylander, who deked around Blackwood and slid the puck past him to tie the game at 2-2 just 19 seconds into the power play.

Brock Nelson restored Colorado’s lead with 7:35 remaining after a chaotic sequence in front of the Toronto net. The Olympic gold medalist battled for the puck and got the final touch, lifting it over Bobrovsky’s right shoulder to make it 3-2.

Then the game turned.

Blackwood surrendered consecutive goals in a 46-second span as Toronto seized control. Nylander scored his second of the period to even the score before Cowan found the back of the net to give the Maple Leafs a 4-3 advantage.

Colorado’s defensive struggles continued late in the frame when Makar was called for cross-checking Marchenko. The Avalanche headed to the dressing room trailing by a goal and facing a penalty kill to start the third.

Despite holding a 24-12 advantage in shots on goal through two periods, Colorado had little to show for its offensive pressure.

The game returned to even strength after Makar’s penalty expired.

At 6:41, Toronto forward Brandon Duhaime was called for tripping Josh Manson. After the whistle, Zach L’Heureux got into it with Duhaime along the boards, prompting the Toronto forward to respond with a punch. Both players received roughing penalties, while the initial tripping call gave Colorado a power play.

Past the halfway point of the period, MacKinnon was called for tripping Matthews. The Toronto captain made Colorado pay, scoring his second power-play goal of the night to extend the lead to 5-3.

The Avalanche’s penalty troubles continued when Fedor Svechkov was called for tripping Matthews, giving the Maple Leafs another man advantage.

Matthews added an empty-net goal to seal the deal, as Colorado closed out its one-game homestand with a disappointing loss.

The defeat marked Colorado’s second regulation loss of the season, despite outshooting its opponent in both games. On Oct. 7, the Avalanche fell 3-2 to the Winnipeg Jets despite holding a 34-19 advantage in shots. Against Toronto, another edge in shots couldn’t make up for defensive breakdowns and five goals allowed.

Colorado now turns its attention to a critical back-to-back against the Dallas Stars, beginning Tuesday on the road before the teams meet again Wednesday at Ball Arena. Puck drop for both games is scheduled for 6:30 p.m. local time.