It’s only the rarest of hockey games that features three periods of up-and-down, high-scoring, roller-coaster action, and then continues with nearly a full game’s worth of scoreless, grind-it-out attrition.

But that’s exactly what the 1,013 in attendance at the

Bright Hockey Center on Saturday were privileged to witness as No. 4 Harvard (25-6-3) came from behind to best No. 6 Mercyhurst (28-7-2), 5-4, in triple overtime and advance to the NCAA Frozen Four this upcoming weekend.

After senior tri-captain Nicole Corriero erased several Laker leads with four goals in regulation, she delivered the dish to linemate Julie Chu on a 2-on-1 breakaway for the game-winning tally 12:28 into the third extra period.

“Our conditioning came in as a factor,” Corriero said. “And Julie was able to find that bit of energy and make a sick move, thank goodness.”

With the puck deep in the Harvard zone, freshman Sarah Vaillancourt received a pass and carried the puck across the Crimson’s own blue line before feeding a streaking Corriero on the right side. Corriero drove up the ice along the right boards and angled towards the net, forcing Mercyhurst goalie Desirae Clark to commit at the right post before crossing to Chu, who lifted a backhander over Clark into the net.

Chu leapt in the air in celebration following the goal. She was immediately mobbed by her joyous teammates and jubilantly applauded by the hearty Harvard fans that had sat through the longest game in NCAA tournament history and were rewarded with a thrilling victory that prolonged the Crimson’s national title hopes.

“We always say, ‘We’ve got lights on this pond,’” Chu said. “It was two games’ worth of hockey that people really battled out, and hats off to Mercyhurst and our team for being grinders.”

The Chu strike broke a stalemate that had lasted since Corriero tied the game just 38 seconds into the third period. On that goal, the second of the team’s two scores at 5-on-3, Corriero cleaned up the rebound from a Vaillancourt slapshot and tucked it past Clark to knot the contest at 4.

From that point on, the game evolved into a defensive struggle headlined by the record-setting performances of the two goalies.

Clark, a senior, posted historic numbers in her final collegiate appearance, with a national single-game record 78 saves, including a number of acrobatic stops on the sporadic Harvard flurries that spotted the overtime periods.

“I doubt if I’ve seen a better goaltending effort this year,” Harvard coach Katey Stone said. “Or in many years.”

While Clark gave her team a chance to win, Crimson junior netminder Ali Boe rebounded from a shaky opening frame to stonewall the Lakers attack, posting 77:08 of shutout hockey down the stretch and her second-straight career-high in saves, racking up 56.

“She bounced back and she was tremendous the rest of the way,” Stone said. “She came up with some huge saves.”

Together, the duo saw 143 shots on goal, shattering the previous record from the 2003 NCAA final. Harvard’s 83 total shots and 21 in the second period were both team highs.

Boe’s travails early on, however, allowed Mercyhurst to build a quick lead, heading into the first intermission with a 3-1 advantage. A lucky break for the Lakers got them on the scoreboard first, when Samantha Shirley’s pass deflected off a defender’s skate past Boe for the unassisted goal. The lead doubled less than three minutes later when the puck trickled over the line after a scrum at the left post.

Harvard was bailed out, as it continued to be throughout regulation, by Corriero and the top power-play unit.

“Their power play is tremendous,” Mercyhurst coach Michael Sisti said. “And they gained some key momentum off their power-play goals.”

Afforded a 5-on-3 advantage with five minutes left in the initial period, the Crimson cashed in the opportunity. Chu picked out Corriero at the left post to bring Harvard within one.

The deficit soon surged back to two when a turnover in the zone ignited a Mercyhurst 2-on-1. Stefanie Bourbeau gave it up to CHA Player of the Year Teresa Marchese, who beat Boe glove side.

Down two goals with its entire season on the line, Harvard was not discouraged, and instead drew inspiration from a season-long string of peaks and valleys, knowing it had the strength to recover.

“This game was like our season has been,” Stone said. “We started off shaky and dug ourselves a hole and then we climbed out of it. We were very consistent and then we became attacking.”

In that frame of mind, the Crimson stormed out of the gates in the second period, with Corriero jamming home another rebound.

A similar play unfolded minutes later, when Corriero nailed down the hat trick on assists from Chu and sophomore Caitlin Cahow.

The deadlock was short-lived, with Mercyhurst earning its last lead at 4-3 with 4:40 left in the middle frame—erased early in the third by Corriero’s last tally.

Corriero finished with five points and four goals in all, both single-game tournament records. Chu had a goal and three assists on the afternoon, and Vaillancourt also contributed a trio of helpers.

In the end, the bruising, interminable encounter exposed the heart and determination of all the athletes involved, who pushed themselves through 112:28 of do-or-die hockey.

“It’s playoff time, it’s do-or-die, and anything can happen,” Corriero said. “I was facing potentially the last game of my hockey career and you find that inner strength to go that extra bit because you don’t want it end.”

Harvard will now travel to Durham, N.H., to tackle conference rival St. Lawrence in the Frozen Four at 5 p.m. on Friday.

—Staff writer Jonathan Lehman can be reached at jlehman@fas.harvard.edu.