Gilman recorded seven shutouts and surrendered only two goals in its first nine games.
So what happened to the Greyhounds Saturday, shook them up.
Haverford, of Pennsylvania, blanked host Gilman, 3-0.
The Powerade Fab 50 ESPN High School poll ranks Haverford 32nd in the nation, but Gilman (8-1-1) is just as talented and holds down the 15th spot.
"They outworked us and deserved to win," Gilman coach Jon Seal said. "We were reeling a little bit. We played four games last week and three games this week. That's not to make excuses, but our kids just didn't have the legs they did."
Haverford's Nate Arronson gave his team a 1-0 lead in the 24th minute, beating All-American goalie Andrew Harris to the left post.
Carlo deMarco bumped the score to 2-0 in the 35th minute, knocking in a crossing pass from Sam Rohr.
"As the longer the game went on, we were able to generate some chances because we have some really good attacking players," said Haverford coach Bill Brady, whose team improved to 7-0 and hasn't allowed a goal all season. "Getting the goals early forced them to starting pushing forward. It gave us a little more of an opportunity to hit them on the counter attack."
Gilman's best scoring chances came early the second half. The Greyhounds hit the post twice and a goal was disallowed because they were offsides.