Clemson shattered American University's hopes of an NCAA soccer semifinal berth today, snapping the Eagles' 16-game unbeaten streak with a goal midway through the second half for a 1-0 quarterfinal victory.

The fifth-ranked Tigers (15-1-1) will make their fourth appearance in the final four next Saturday in Tampa, Fla., against Columbia (14-2-1), which beat Rhode Island today, 5-1. Southern Illinois-Edwardsville and Penn State will square off in the other semifinal.

Obed yariri, who doubles this year as Clemson's football placekicker, scored his 14th goal of the season with 18:37 left off an assist from midfielder Marwan Kamaruddin for the game's only score.

Up to that point, American (14-3-4) had shut down the vaunted Tiger offense and was proving more than a match for the eight-time Atlantic Coast Conference champions.

"I defintely think we should have beaten them," said American midfielder Doug Dugan, who, with teammate Luis Calderon, played a major role in sparking the Eagles. "This was a team effort -- ours -- against on individual effort. These guys, don't mark you, and if you don't panic, you can do anything you want."

Clemson Coach I. M. Ibrahim, whose team humiliated American, 4-0, in last year's Southern Region final, showed even more concern for his team's showing, particularly that of striker Nnamdi Nwokocha. The freshman standout, who came into the game with 24 goals, did not even get a shot off until 20 minutes had elapsed in the second half.

"We were very off our game today," Ibrahim said. "It was one of our weaker performances of the season. We made bad passes, and when we weren't doing that, we made the wrong passes. That's not to take anything away from American. They're one of the best teams we've faced this year. We had to fight our hearts out.

"I though Nnamdi had a miserable game," Ibrahim added. "I'm not pleased with his performance at all."

It was not all Nwokocha's fault. From the start, the ACC's most valuable player was well defended by Terry Schrider, pressed into a starting role because of Scott Turner's lingering ankle sprain.

It was one of three planned defensive changes made by Coach Peter Melhern. The others were starting Keith Tabatznik for Alex Kozlov (mononucleosis), at right back and replacing Tabatznik with midfielder Bill Hylton in the second half.

Together with sweeper Charlie Davis, left back Tom Tague and mid-fielder Eduardo Lopez, the American defense kept Nwokocha and Ariri from doing any serious damage throughout the first half.

American, which played conservatively throughout most of the first half and was outshot, 9-5, picked up the offensive thrust in the second. Calderon's fancy footwork and Dugan's pinpoint crossing kept Eagle forwards Mark DeBlois, Kevin Barth and Jim Pidemont within shooting range.

The Eagles evened the shot tally at nine after 20 minutes of the second half, but Clemson backs Joseph Awesu and Damian Odoh and keeper John Bruens were not easily beaten. When a loose ball spurted out to Kamaruddin near midfield, the transition phase that aided AU so much in the early going caught the Eagles off guard.

"Our midfield was all up and their fullback intercepted a pass," Dugan said. "We were going one way and he (Kamaruddin) was going another. There was 50 yards ahead of him with no one to challenge."

Kamaruddin, whose individual efforts highlighted Clemson's offensive attack, dribbled down the middle before feeding Ariri near the top of the penalty area. The 5-foot-9 senior from Nigeria then ducked Lopez's tackel and sent a ground shot to the far right corner past American keeper Bill Ruvo for the tally.

The goal was the first in the last seven games against Ruvo, who has posted a school record nine shutouts en route to a 12-1-2 mark in goal. He made seven saves against Clemson's 11 shots and was an alert recipient of many Eagle back-passes, especially from Calderon in the second half.

Clemson began picking up its movement after Ariri's score but the Tigers, who last year outshot American, 29-3, still had defensive work ahead. Bruens did his busiest work in the final 12 minutes, diving left to stop a blast by Dugan off an indirect kick from 30 yards and picking off a line drive by Hylton with 30 seconds left.

"This year we're 100 percent improved. We knew we could play with these guys and I think we proved it. Last year we just panicked," said Dugan, one of seven Eagle seniors. "I don't think we have anything to be ashamed of."