Of all their many weapons, the Boston College Eagles have struggled on the power play for much of the season, poking along with a meager success rate of less than 20 percent, looking to find their man-advantage mojo.

By the looks of Monday night’s 3-2 win over Harvard in the Beanpot tournament opener at TD Garden, they may have found it.

“Greg Brown works very closely with our power play,’’ noted BC coach Jerry York, referring to his associate head coach. “He’s tried to establish a ‘no-dust’ rule. When there is too much stickhandling, it’s dusting [the puck] back and forth, back and forth, and what that leads to is a stagnant power play. So we are trying to go tape-to-tape-to-tape without stickhandling. And I think that was a big change in our power play.’’

Big change and two bigger goals, both scored in the second period when the Eagles erased a 2-1 deficit and posted a 3-2 lead they carried to the end. Zach Sanford scored the first at 6:05 to pull the fourth-ranked Eagles into a tie, and Colin White followed 4:24 later with what turned into the winner.

The Eagles, who won the Beanpot for five straight years before Boston University’s victory last year vs. Northeastern in the title game, will be back in the championship game next Monday for a ninth time in the last 11 years. They’ll face BU, which defeated Northeastern, 3-1, in Game 2 Monday night.

“We didn’t get the amount of zone time and possession of the puck we needed to create more offense,’’ said Harvard coach Ted Donato, the former Bruins winger, whose club went 0 for 2 with its man-advantage chances. “We’re frustrated that we didn’t execute the way we need to to be more successful.’’

Harvard, without a Beanpot championship since 1993, last played in the title game in 2008 — a 6-5 OT loss to the Eagles.

“We knew we were in a good spot headed into the third period,’’ added Harvard captain Kyle Criscuolo, encouraged by how the Crimson took the 2-1 lead in the first and were still in the thick of it even after BC’s pair of power-play strikes. “We knew we needed to have a good third period, but we came up short.’’

The Crimson pulled goalie Merrick Madsen for an extra skater with a minute to go in regulation, but only added an extra skater (Sean Malone) for some 10 seconds before a whistle forced Madsen back in net. The Eagles then prevented Harvard from getting a shot over the final 44 seconds and ended up outshooting the Crimson, 33-23.

The Eagles are 18-4-4 and have not lost since a 2-1 defeat by Providence on Dec. 29. The seventh-ranked Crimson, who had been riding a three-game winning streak, fell to 12-5-3.

“I thought we did a thorough job in all three zones,’’ said York, emphasizing that he liked his club’s performance on the “compete’’ and “energy’’ levels, as well as overall game structure. “I thought our structure for the most part was solid tonight.’’

Undefeated in January (4-0-3), BC knotted it when Sanford potted one from the doorstep after Ian McCoshen sent in a long wrister from near the point slot. Alex Tuch had an initial attempt on the rebound, but it was left for Sanford to provide the final touch near the right post at 6:05.

With Harvard defenseman Clay Anderson in the penalty box to serve an interference call, White, the high-scoring freshman (now 16-19—35), walked out of the left-wing faceoff circle and shoveled home a short-range forehander for the 3-2 lead.

Harvard was painfully slow to generate shots in the first period, but its first two attempts made it by Thatcher Demko (17-4-3), allowing the Crimson to carry the 2-1 lead into the first break.

Paced early by an effective forecheck, the Eagles moved to a 1-0 lead with only 95 seconds off the clock. Casey Fitzgerald, set up by brother Ryan’s backhand feed out of the left corner, connected with a slapper from the top of the left-wing circle.

The Crimson finally landed a shot on Demko at 9:47 and it was Ryan Donato, son of the Harvard coach, who potted the equalizer from low in the slot. Donato came rushing down the middle with a Tyler Moy feed and knocked his shot by Demko just ahead of an onrushing White.

Less than five minutes later, freshman Adam Baughman, playing in only his second game for the Crimson, wristed home the 2-1 lead from above the right-wing circle. The shot came just as Demko got himself upright after a goalmouth collision with Jimmy Vesey. The play went to video review, which showed Vesey, although he still had a skate in the crease, did not impede with Demko’s chance of stopping the puck. Baughman’s shot broke in off the big stopper’s right pad.

“They made it tough on us all night,’’ said a sullen Donato, yet to lead the Crimson to a Beanpot championship during his tenure. “So give them credit.’’

Kevin Paul Dupont can be reached at kevin.dupont@globe.com. Follow him on Twitter @GlobeKPD.