Three weeks ago, Mike Mansy of T.C. Williams found himself in a strangely familiar situation. It was the Georgetown Prep Cross Country Classic and with barely 1,000 meters to go, Mansly was in second place - just as he had been the year before.

But unlike the 1976 race, where he remained the runner-up, the Titan junior mustered a furious spurt of energy, caught the leader and dashed over the final slope to first place.

It was just one of nine straight triumphs for Mansly this season, a slate unmarred by any losses. He extended that undefeated string in yesterday's Northern Virginia AAA Regionals and top contender for the state title next Saturday. Regardless of the outcome, Saturday in Charlottesville.

"I wasn't really a racer last year," said the 5-foot-6 1/2, 110-pound harrier, who still managed to finish seventh in the 1976 regionals and win the Alexandria City meet. "This year I have the drive and I'm more sure of myself. I really want to be No. 1."

Mansy admits there's a lot of pressure at the top. But he thrives on it.

"People are always trying to psyche you out," he said. "At the beginning of the season, I heard some coaches next to me say that wasn't going to be good until next year. That just made me want to be even better this season. Some of my competitors have said I'm not going to be able to keep on winning. That's just fuel on the fire."

Mansy's kinship with pressured situations isn't surprising. Starting at age 11 he combined school, homework and recreation with long hours in his father's grocery store and his uncle's pizza shop. His father, Fahmi, had been a long distance runner in Iraq byt Mansy planned to follow the route of his two older brothers. Two older sisters and a variety of relatives into the family's bustling businesses.

Things changed quickly when he entered ninth grade at Hammond Secondary, a ninth and 10th grade school which feeds into Williams. Bob Adkits, the school's cross-country coach, needed someone to replace an ailing runner and he had heard glowing gym class reports about a kid named Mansy. By the end of the first week of school, Mansy, who never had run competitively before, was suited up and running as a team's sixth man.

It didn't take long for him to make up for the lost time. With enthusiatic backing of his father, Mansy began to spend his autumn afternoons logging mile after mile on countless Alexandria's streets. When the annual NCAA scholastic cross-country nationals rolled around in December, he surprised everybody but himself. Mansy passed his entire team and finished 30th of nearly 200 runners.

The next year, he was pulled up from Hammond to run for Williams. The school's cross-country coach Mike Tomasello, knew right away that he had a potential champion.

"I had watched him run at Hammond and was very impressed," said Tomasello. "Even then, he ran extremely fluidly and economically. He put in backbreaking hours and just kept improving.

Mansy won most of his dual-meet-matchups but funished a disappointing fifth in the Northern District Championships, while the Titans finished in the lower half of their division. That summer, following a third-place finish in the state two-mile track championship, he tried something new. He got together with some friends and began rigorous daily workouts down the George Washington Parkway, agonizing through 10 miles, then 14 and later 20.

The payoff began this season. Mansy traveled to Charlottesville for the University of Virginia state high school cross-country invitational. With a host of family members cheering him on, led by his 69-year-old Lebanese grandmother, he won the race beating favored Chuck Wimberly of Edison. Convincing victories at Prep and Handley followed and Mansy was on his way to establishing himself as the region's powerhouse.

His winning habits seem to have worn off on his team. Two weeks ago, Williams notched first in the district championships and is a serious candidate for the top honors of the region.

"There's no doubt in my mind that the team's turnaround is due largely to Mike," said Tomasello. "Although he's had the spotlight, he runs for the team. He demands a great deal from himself and from his teammates. He's not the biggest guy you'll ever see but he runs very tall."

Mansy considers himself lucky to have had a chance to engage in athletics, unlike his elder siblings. He still spends each Sunday flinging pizza dough and slicing subs, but he plans to move on eventually.

"I'd like to study government, I think," he said. But whatever I do, I want to run cross country forever."