It was a sight nobody was sure they would ever see — at least not this season, anyway. 

No, this isn’t about Tyler Seguin getting time on the power play, though we’ll get to that. The image is something far more surprising. We’d seen Seguin on the power play recently in practice. Seeing the rookie out on the man advantage was hardly as shocking as this.

Picture a wild TD Garden in which onlooking fans are using their fingernail-less hands to cover their eyes. There’s less than two minutes to play in a critical playoff game with the team desperately hanging on to a one-goal lead (which had been a three-goal lead). 

In that moment, Tyler Seguin was on the ice. 

No, Claude Julien was not asked the “Who are you and what have you done with Claude Julien?” question following the game, because the reasoning was too obvious. Julien was rewarding a player who simply exploded Tuesday.

Seguin’s four points (two goals, two assists) in the second period of Tuesday’s 6-5 win over the Lightning made his Game 1 performance (a highlight-reel goal in the first period and an assist in garbage time) look like an off night. He was fancy, smart and increasingly confident all at once. Above all, he was dominant. 

“He was really the reason we won tonight,” straight-shooting winger Brad Marchand, who has a better chance of starting a folk duo with Max Pacioretty than saying anything but the truth, said of Seguin’s performance.

Seguin has used the limited time he’s been given in the postseason to make people see where, at 19 years old, he currently stands. He’s a kid, and man, is he a liability defensively. Yet Seguin has taken the last two games — his first after sitting 11 games to begin the postseason — to remind not only Julien but anybody else caring to watch what else he is. He’s a scorer, a playmaker and a highly, highly explosive player.  

“He was extremely good tonight — there’s no doubt about that,” said Julien, who has been bashed by some for his handling of the rookie, following the win. “One of our best players out there. He used his speed very well tonight. He challenged their D’s with it, did a great job. And it was nice to see him respond that way. He’s competed extremely well and he’s been an excited individual waiting for his opportunity, and he’s certainly making the best of it.”

People had been getting angry at the conservative Julien, not because he wasn’t playing Seguin but because they knew he wouldn’t play him. It was predictable. A kid who turns it over and doesn’t play sound defense does not sound like someone Julien would want out on the ice, especially in playoff time. It was also predictable because Julien believes so much in a player proving himself and then being rewarded. Seguin hadn’t proven himself in the regular season, so there would be no reward. People may have disagreed, but they all knew it was going to happen. 

Yet on Tuesday, Seguin took matters into his own hands. The youngster played less than three minutes in the first period, but when he went out for his first shift of the second period he split two Lightning defenders and scored his second goal in as many games. Two shifts later he scored again. Julien liked what he saw, and the coach increased the rookie’s power-play time.

It didn’t seem anything was going to faze Seguin on Tuesday, and in the end nothing did. Seguin took his power-play shift and made it count. The rookie fired a shot off Michael Ryder’s stick, with Ryder gaining possession and beating Dwayne Roloson. Seguin and Ryder’s fun wasn’t done, as Seguin found Kelly with a nice pass through a defender’s legs to set up another Ryder goal. It was a sloppy game by both teams, and in a contest as disorganized as Tuesday’s was (Guy Boucher likened it to pond hockey after the game), skill won out in the end. Seguin’s skill was never in question, but the ability to utilize it was. He answered on the biggest stage possible Tuesday, and the Bruins now can only wonder what this push for a Cup may look like if they can suddenly get the boost of an effective Seguin. It wasn’t long ago that B’s fans wondered how Seguin could get in the lineup. Now, Lightning players are wondering how they can stop the 19-year-old. 

“I think it was his first goal, he went up the ice, just flying, and that was a nice goal. He was skating hard,” Vincent Lecavalier said after the game. “He is a great skater. He is a smart player. … The first two games for him have been great. We definitely have to keep an eye on him and make sure the structure we play better at and not give those chances."

Seguin’s days of press box duty should be over now that he’s put up six points through two games. He can recall one message a teammate gave him while in the midst of his time as a healthy scratch.

“I remember a specific time when Shawn Thornton came up to me,” Seguin recalled. “It was the beginning of the second round and he just came up to and said, ‘Look, kid, if we’re going to the Cup, you’re going to get an opportunity to play, just because injuries are part of the game. Have fun with it. Enjoy the ride. Take it all in and use it as a learning experience.’ ”

Seguin certainly is enjoying the ride to this point, and it seems he has earned admission now.