On a night when Leafs fans were on the verge of celebrating the accomplishments of their rookies – five different freshmen each scoring once – superlatives quickly turned into expletives.

In an all-too-familiar refrain, Toronto squandered a late third period lead and went on to lose 6-5 in overtime. The crushing defeat came at the hands of the New York Islanders at Barclays Center on Monday night.

When William Nylander – fresh off his Saturday night hat trick – fired home the go-ahead marker with just 2:01 left in regulation, Toronto was poised to skate away with two points as they had done in Boston two nights earlier.

But Toronto’s porous defence meshed with goalie Fredrik Andersen’s recent struggles all but made 121 seconds an eternity for the Islanders to even the score. Indeed, with Thomas Griess on the bench for a sixth attacker, Andrew Ladd got the equalizer just over a half minute later to force overtime.

Brock Nelson tallied his second goal of the game in the extra session to seal the victory.

The Leafs’ youthful talent was showcased yet again. After an early goal by New York’s Ryan Strome to open the scoring, Nikita Soshnikov knotted the affair with a rocket of a shot past Griess in the first period. Toronto took the lead when Auston Matthews scored on an odd-man rush, accepting a pass from Morgan Rielly to net his 24th goal of the season.

Ex-Leaf Nikolay Kulemin evened the score before the end of the opening frame after too many blue and white skaters got caught mesmerized by the puck carrier.

In the second period it was Mitch Marner’s turn to shine. The January Rookie of the Month converted a cross-ice feed from Tyler Bozak to reclaim the lead for his team. Later in the frame, Zach Hyman made history by scoring shorthanded on a 2-on-1, becoming the first Leaf ever to score three shorthanded goals in a season.

But, things turned sour for Toronto after Brock Nelson found the back of the net on what looked like a harmless dump-and-chase into the Leafs zone, beating Andersen just above the shoulder to bring his team within a goal.

The Leafs played the third period like they had no intention of generating any offence. Predictably, the strategy of trying to sit on the lead failed, and Josh Bailey evened the score, setting the stage for the turn of events starting with Nylander’s goal, and ending in defeat for Toronto.

Andersen had occasional flashes of brilliance, but was otherwise flustered, struggling particularly with rebound control. He stopped 26 of 32 shots.

“I think we’re disappointed,” coach Mike Babcock told reporters after the game.”I didn’t think we did that well in Boston but we got away with it and won. In this one here, it’s disappointing. We had the game won and we gave it up.”

The squad has little time to lick its wounds. The Leafs travel home to face Dallas on Tuesday night.