In the biggest game of the year, with a season and a Stanley Cup defense on the line, on a team loaded with elite veteran superstars, it was Brandon Saad — 21-year-old Brandon Saad — who simply wouldn’t let the Blackhawks lose on Wednesday night.

It was Saad barreling through the neutral zone and attacking the net. It was Saad firing pucks on net, attempting 10 in all. It was Saad backchecking like crazy, forcing at least three turnovers. It was Saad keeping up with and making plays with Patrick Kane. It was Saad setting up Michal Handzus’ game-winning goal in overtime.

It was Saad in full — a big, fast, Marian Hossa clone with uncanny strength on the puck to go along with his natural speed and innate confidence and hockey sense, far beyond his years.

“What I saw last night was probably one of his best games I’ve ever seen him play,” said defenseman Michal Rozsival, echoing what everyone — even Saad himself — believed. “Just the way he played with so much confidence. He looked like he wanted to be the guy, the guy that makes the difference in the hockey game. I think he did.”

Kane said he was “awesome.” Jonathan Toews said he was “unbelievable.” High praise from guys who know a thing or two about putting a team on your back in the most pressure-packed of situations.

You hesitate to label it a breakout game for Saad, or call it his coming-out party. The 6-1, 202-pounder has been awfully good from the start, since he became a full-time NHL player in the second game of the 2013 season — thrust on to the top line with Toews and Hossa and fitting right in at age 20. His teammates deemed him the “Man-Child” because of his size, his strength, and, well, his impressive beard-growing ability.

But on Wednesday night, he was simply the Man. He had a goal and two assists and was a plus-4 in the 5-4 double-overtime victory. In 17 playoff games, he has five goals and eight assists and a plus-9 rating. No other Hawks player is better than plus-5.

“He was never satisfied,” Toews said. “He wants to be a difference-maker, and I don’t know if i can think of a game that I’ve seen him play better than last night. He was unbelievable. That’s what it takes. That’s basically what we need to find a way to win against this [Kings] team, is guys like that stepping up.”

Saad and Kane, put on a line with Andrew Shaw in Joel Quenneville’s latest attempt to catch lightning a bottle, were electric together — Saad’s physical, net-crashing style and speed perfectly complementing Kane’s puck-work and vision. Kane had four assists, and Shaw added two. Saad and Kane have shown flashes of that natural chemistry before. In their very first game as linemates, way back in October in Minnesota, Saad set up a Kane goal with a sensational no-look, spin-o-rama pass.

Yet on Wednesday night, in the giddy aftermath of Game 5, Quenneville said the new second line “might have been a discovery.”

“Hopefully what we discovered could be a line for a long time,” Quenneville said.

With Quenneville’s itchy trigger finger, a long time could be a couple of periods into Game 6. But if Wednesday was any indication, Saad and Kane could be making magic together for years to come.

Regardless, Saad — the quiet rookie turned confident beast — appears to be just getting started.

“I feel like that was one of the best games I’ve ever played, on one of the biggest stages,” Saad said. “It was nice to help the team win an elimination game, and I’m looking to keep moving forward.”

Email: mlazerus@suntimes.com

Twitter: @marklazerus