NORTH BILLERICA — It was only four years ago that there were only nine players on St. Bernard’s boys hockey roster. On Saturday at the Chelmsford Forum, the Bernardians completed one of the best turnarounds in recent memory.

Senior goaltender Chase Bergeron dazzled, stopping 44 Winthrop shots while five different players recorded a goal as ninth-seeded St. Bernard’s pulled off the upset of the defending Div. 4 champs, 6-3, to make next Sunday’s state final at TD Garden.

“This is unbelievable,” St. Bernard’s coach Steve Sylvia said. “We’re a small school in Fitchburg with 200 kids in it. And it’s been the last three years building this thing and we knew we were gonna be good. We just didn’t know how good we were going to be.”

For large portions of the game, the Bernardians (21-3-0) found themselves hemmed in their own end. But Bergeron was there every time his team needed a big stop, leaving the Vikings (15-7-2) shaking their heads many times.

“I mean, he’s just awesome. He was just awesome. I wouldn’t want to have to shoot against him,” Sylvia said.

The Vikings broke in top just 4:20 in when Bert Kline converted off a net-mouth scramble. It stayed 1-0 into the final minutes of the first period when Matt Sylvia raced down ice and ripped home his 36th goal of the season to tie the game at one.

Winthrop, however, seemed to take the momentum back on the next shift as Charlie Ferreira fired home a Braedon Lounsbury rebound for a 2-1 lead after one.

It seemed like the Vikings were about to run the Bernardians out of the barn as they began a 19-shot second-period barrage. Bergeron, however, made several critical saves to keep it 2-1.

Will Canada gave St. Bernard’s a huge lift when he tipped home Owen Tolson’s left-point blast at 3:02 to tie the game. It proved to be an omen as the Bernardians would make good use of the five shots they got in the middle frame.

Winthrop had a golden chance to go back in front with 32 seconds of a two-man advantage, but they failed to convert. The Bernardians’ talented forwards made them pay for it late in the period.

Phoenix Fortier, who was brilliant all game, netted his 22nd of the season at 12:19 to give his team its first lead of the night. On the next shift, Evan Walker crashed the net and earned his 23rd goal of the year off a loose rebound, which stunningly gave St. Bernard’s a 4-2 lead after 30 minutes.

Desperately in need of two as the third period ticked away, Winthrop’s Joe Pumphret took a deflected shot and fired it into an open net with 7:34 left to cut the deficit to one.

Into the spotlight stepped Toby Beaulac as he found a loose puck between a defender’s skates and ripped one past James Lyman to restore the two-goal cushion. Fortier added an empty net marker with 1:55 left to clinch it.

“You don’t need the best players, you just need the right ones,” Steve Sylvia said. “The right ones came to this school.”