One American collegian will replace another on the Montreal Canadiens' defense for tonight's Stanley Cup game at Boston and it is unlikely anyone will detect much difference.

Brian Engblom, 23 year-old University of Wisconsin product, will skate alongside Guy Lapointe in place of Bill Nyrop, the 25-year old Notre Dame graduate who suffered an eye injury during the Canadien's 3-2 overtime victory over the Bruins here Tuesday night.

Nyrup was hospitalized yesterday with a corneal abrasion of the right eye, as well as mild iritis. He was struck by Rick Middleton's stick with less than three minutes remaining in regulation time. Middleton, in the Process, stole the puck from Nyrop and fired a testing shot at goalie Ken Dryden whose save preserved the tie.

Montreal used only three defensemen - La pointe, Serge Savard and Larry Robinson - for the 16 minutes it took Guy Lafleur to produce the winning goal, at 13.09 of overtime. If the trio was weary, it didn't show, and a rush by Robinson set up Lafleur for the winner.

Montreal swarmed all over the Bruins in the extra period, firing 15 shots at Boston goalie Gerry Cheevers, who performed miracles before Lafleur beat him. In a stretch of less than a minute, Cheevers stopped five shots, the last three after losing his stick.

"I know I played well," Cheevers said,"but a loss is a loss and that cancels out everything. And it's a shame, a real shame, because these guys played their guts out."

There was a feeling in both camps that the battling Bruins had come close to making a competitive series out of it, but with their failure they might have trouble rising to those heights again.

"That goal is the biggest goal of the year," Savard said. "It's worth two games. If they would have scored it, we'd lose the home advantage. We work 80 games for that and lose it in fractions of seconds."

The Bruins have slight advantage in Boston, where game three will be played tonight and game four Sunday night. Boston Garden, only 83 feet by 191 feet instead of the standard 85x200, is the smallest ice surface in the NHL.WIth less room behind the nets, the swift Canadiens have reduced skating potential.

"There's less room to maneuver. They can stick to you better there," said Lafleur.

Lafleur did not mention the animalistic Boston crowd, which can intimidate lesser players. Lafleur seems to play better as the challenge grows and, last year in Boston, he either scored or assisted on all six Montreal goals as the Canadiens completed a four-game sweep of the Bruins.

Boston Coach Don Cherry, as usual, was outwardly optimistic, saying,"After that game, we know we're in the same league with them. On the smaller ice, we don't have as far to chase them. It won't be easy, because they did pretty well in our risk before, but we're going back with a lot of confidence."

Of their last 13 games against Montreal, including five at Boston, the Bruins khave won none, with one regular season tie.

Cherry was unsympathetic when he learned that Nyrop would be unable to play.

"Gee, the poor fellows," he said. "Now they'll be stuck with (Rick) Chartraw and (Pierre) Bouchard, who could make any club in the league."

He had forgotten Eugblom, who has seen limited service in 26 regular-season contests and four Cup games. A year ago, Engblom was voted best defenseman in the American Hockey League, so he could probably play regularly for a few NHL clubs, too - certainly for Boston.