St. Lawrence's Paul Castron kicked the Harvard men's hockey team back into its own three-goal hole with a game-winning goal 39 seconds into overtime last night at Bright Center.

The 4-3 setback dropped Harvard (17-6-2 overall, 14-5-1 ECAC) into a tie for third in the ECAC.

After the Crimson had stormed back from a 3-0 deficit in the final nine minutes of regulation, Castron spoiled the miracle comeback with an extreme angle score on the first shot of the extra period.

Castron and linemates Chris Gunnarson and Benoit Quesnel broke into the Harvard zone with a three-on-two. The puck bounced across the slot. Brad Kwong went down to block Castron', shot, but Castron faked and angled in on net.

His backhand shot somehow beat Harvard goalie Grant Blair, scuttling the Crimson's comeback and shocking the sellout crowd of 2850.

Tonight's opponent, Clarkson, topped Dartmouth, 4 2, last night to give the Golden Knights (15-5 ECAC) a half-game edge on Harvard and Cornell.

A Harvard victory tonight (Bright Center, 7:30 p.m.) in its final regular season game would make the Crimson the second or third seed for next week's playoffs (see box)

"We played for 10 minutes, not for 60," Harvard Coach Bill Cleary said. "We weren't ready to play, but this is the one to lose, if you have to lose one."

A loss against Clarkson tonight would make the Crimson the fourth playoff seed, setting up a showdown with fifth-place Yale in next weekend's quarterfinals.

In the first two periods last night, it looked like Harvard was en route to its first shutout loss since December 1983. The Saints produced three goals with a careful defensive strategy, and freshman goalie Scott Yearwood shut down the Harvard offense.

While the hours played well enough to create some excellent chances in the first 40 minutes, they failed to get many rebounds, as the SLU defense repeatedly cleared the puck from in front of the net before Harvard could get a rebound try.

After first-period tallies by Gunnarson and Quesnel hoisted the Saints to a 2-0 advantage. Bruce Robertson, playing in his second game in two years, appeared to the game when he banged rebound with just 10 seconds left in the middle stanza.

Although Blair and several Crimson defensemen seemed to have the puck frozen a number of times, the visitors kept swarming and Robertson earned a key score to give his squad a 3-0 advantage.

"We gave up a bad goal at the end of the second period and it came back to haunt us," Cleary said.

Midway through the final stanza the Crimson still hadn't managed to beat yearswood.

"It got down to 10 minutes left, someone had to make something happen," center Scott Fusco said. That someone was Fusco, and that something was a goal off a nifty pass from Lane MacDonald in the left corner Fusco, working double shifts, struck again three minutes later, knocking in a backhand rebound of a Rob Ohno point shot.

The goals upped Fusco's consecutive games with a point streak to 24, trying him with Coach Cleary's brother Bob in the Harvard record book.

The second Fusco goal cut the St. Lawrence lead to one and gave the Crimson the momentum it had been seeking all evening.

After a couple of excellent opportunities, freshman Don Sweeney connected on the game-tier from the blue-line at 17:14.

"Lane [MacDonald] had it in the corner," Sweeney said after scoring his second goal of the year. "He got it from Scotty [Fusco], who sees everybody on the ice, and he banked it to me.

"I shot and the puck went through about 15 legs."

After Tim Barakett missed the SLU net by less than six inches with time running but, the Crimson flew into overtime on a three-goal roll.

Castron ended any hope of a Harvard victory, however, with his quick goal. (Saints, 4-3 OT) at Bright Center St. Lawrence  2  1  0  1--4 Harvard  0  0  3  0--3

First Period Gunnarson (Paul) Castron Tom Pratt) 4-03-2, S. Bc. Queuesnet 1-1 (Gunnarson Castron) 1 12 Penalties astron, S (hooking) 28, Scott Nickerson. S (roughting) 6 28, Rick Mulligan. S (hooking) 11 39, Don Sweemcy. H (holding)

Second Period S. Bruce Robertson I (Dave Saunders, Nickerson) 19 50 Penalties Todd Petkovich, S (holding) 2 12; Gunnarson, S (roughing) 11 28, Brad Kwong, H (high sticking) 11 28, Mulligan, S (cross-checking) 12 03, Peter Follows, H (roughing) 18 10, Perkovich (roughing) 18 10.

Third Period 4, H. Scott Fusco 27 (Lane MacDonald Kwong) 11 15, 5, H. Fusco 28, (Brian Busconi, Rob Ohno) 14 10 6, H. Don Sweeney 3 (MacDonald, Fusco) 17 14 Penalties Tim Lappin, S (boarding) 11-25; Castron (delay of game) 12 56.

Overtime - 7 Castron (Quesnet, Gunnarson) 19 Penalties--None.

Saves S. Scott Yearwood 7 12 11 0 30, H. Blair 4 11 8 0 23 A--2850.