One thing was evident in the 165-team Reston International soccer tournament yesterday -- teams that had played against international competition were a step ahead of those that had not.

"I could have told you yesterday just by seeing the teams which four would be in the semifinals," said Rockville coach John Bernas after his 1964 boys squad defeated McLean, 1-0, yesterday morning at the Loudoun County campus of Northern Virginia Community College. The victory earned a meeting with Forest Park of Cincinnati in the semifinals, a game won by Forest Park, 2-1.

Reston played well in the quarter-finals but could not overcome Forest Park's strengths, dropping a 2-1 decision. McLean, which earned the wild-card spot in the semifinals, rallied over Fairfax, 4-1.

The victory over McLean was the third tournament win within 24 hours for Rockville, which is undefeated locally in the National Capital Soccer League.

Forest Park defeated Trenton (N.J.) yesterday morning, 1-0, for its third victory. McLean defeated Raleigh (N.C.), and Kirkwood (Del.), earning the wild-card spot. Fairfax clinched its semifinal berth with a 4-2 win over the Reston Atoms earlier in the day.

McLean and Forest Park will meet in the finals today at 11 a.m. on the Loudon County Campus. Other division finals featuring teams in age groups between 9 and 19 will start at 9 a.m. at Loudoun County Campus, Lake Fairfax and Hutchinson Field.

Both Rockville and McLean have been on European training tours within the past two years. Bernas said what American players can learn from international competition is immeasurable.

"Skills -- that's what we (Americans) are lacking," he said after Shannon Perry's 12-yard chip shot 10 minutes into the first half floated over the head of McLean goalie Scott O'Brien for the game's only goal.

"You can teach these kids tactics, but the boys aren't using their skills. Now we control the ball. We keep it on the ground."

Bernas credits a trip to England, where Rockville trained with the professional Division 2 Cambridge United team and went undefeated in eight games against British competition.

But Rockville struggled against McLean, a winner of its division last fall in the National Capital Soccer League. Coach Gil Smith's McLean team is composed of players "playing up" (against older players), and they came back from a tour of England and Scotland last year with a 5-3 record.