AMHERST--When the Harvard-UMass women's soccer game ended yesterday with an overtime score of 4-3, your first reaction was merely to savor the exciting, aggressive styles of both teams. Then, like a bitter aftertaste, you remembered that the Crimson had lost its first game of the season.

Yet even though the Harvard booters lost, they were not beaten. Rather, the Minuteman got one more break.

"In the overtime, both teams were going for the long ball--for the home run," UMass coach Arnie Morse said after the game. "We hit it and they didn't, and that decided the game."

Minuteman freshman Natalie Prosser notched the game-winning goal on a counterattack breakaway run at 7:15 in the first half of the 20-minute overtime. Harvard goalie Wendy Carle, who made a season record total of 21 saves, started to come out of the box but hung back at the last second, allowing the 1978 Globe-All Scholastic MVP player to angle a ground ball into the net.

One of six starting freshmen on the UMass team, Prosser's aggressive style and good acceleration made her a highly effective player in a game where "the purpose of play wasn't as important as reacting to a situation," coach Bob Scalise said.

"The size of the field made it more an opportunist's game than a game of planned attack," he added.

The Minutemen's field measured 20 yards shorter and 10 yards narrower than the Crimson's home field. This length--or lack of it--reduced midfield play, which increased both congestion in the goal areas and scoring opportuiities.

Seeded first in the upcoming Eastern tournament with a season record that now stands at 10-1, UMass started applying pressure as soon as the game began, scoring first at 7:55 and again at 9:05 in the first quarter.

After her team brought the ball down the field on three throw-ins, 1978 Minuteman high-scorer Elaine Contant crossed the ball to the middle of the field from where freshman Marjorie Anderson knocked it into the net. A few exchanges later, Contant centered another pass, which Prosser banged into the left side of the goal.

"We came out nervous and tentative, and that's what got us into the hole," Scalise said.

But the Crimson's nervousness over playing the one team that beat them last year soon wore off and at 22:15 Cat Ferrante put Harvard on the scoreboard. Streaking across to the left-hand side of the field from her right-wing position, Ferrante picked up a punt from goalie Carle, dodged a defenseman and rammed it home to set the halftime score at 2-1.

"When the score went to 2-1, I knew the next goal would really count," Morse said. "When it went to 2-2, I knew we were in for a battle."

Not used to playing catch-up ball, the Crimson jumped for joy when tri-captain Julie Brynteson tied the game on a heads-up play--lofting a direct kick quickly and precisely into the net while UMass goalie Kelly Turner stood gaping.

The elation, however, was short-lived, as UMass jumped ahead for the second time when Posser hit a high floater from about 20 yards out at 2:55.

If it's hard to come from behind once, it's two times as hard to come from behind twice. But the team that had compiled a 10-0 record previous to yesterday's game and is seeded fourth in the Easterns met the challenge when Brynteson tallied her second goal at 3:07 on a follow-up play.

Although the Crimson continued to threaten the Minutemen until the horn sounded in overtime, several good scoring opportunities developed into "if onlies" instead of goals.

"After a game like this you walk away feeling good," Morse said. "But you're also aware that the shoe could have been on the other foot."