Oakland Mills junior Marvin Williams has worked on his dunking all season during practices, but until Thursday night, he’d never dared to attempt to throw one down in a game. When Williams broke into the open court in the third quarter of the Maryland 2A South quarterfinal against Gwynn Park, the timing suddenly seemed too perfect not to go for it.

With a Yellow Jacket in close pursuit the layup might have been the high-percentage play, but the guard rose for a right-handed slam that whipped the capacity crowd in his home gym into more of a frenzy.

Everything seemed to work for No. 9 Oakland Mills in a convincing 73-45 victory over Gwynn Park in Columbia. The Scorpions kept their unblemished record intact thanks to balanced scoring and a smothering defensive effort in a game they led by as many as 34 points. They will host Largo, which beat Marriotts Ridge, 70-63, in a region semifinal on Tuesday.

“I wanted to go up strong, but I wasn’t sure what I was going to do,” said Williams, who finished with 12 points. “Then I was like, ‘We’re up and it’s the playoffs, so I’m going to try and dunk it.’”

The emphatic victory helped avenge some painful history for Oakland Mills, which remains the only undefeated public school team in the state.

Two years ago, the Scorpions won their first 25 games of the season before Gwynn Park beat them, 52-48, on the same floor in the region final. The Yellow Jackets eliminated the Howard County school three straight years starting in 2009, twice with a state tournament berth on the line.

None of the current Oakland Mills players were around for any of those games, but 2010-11 All-Met Player of the Year Greg Whittington, now a Georgetown sophomore, was in attendance and briefly addresses the team at halftime.

“I didn’t talk much about [the history] because they don’t know,” Oakland Mills Coach Jon Browne said. “They don’t have a care in the world. They don’t think anyone can beat them, and I don’t want to burst their bubble.”

Indeed, Oakland Mills (22-0) left little doubt this time, building its advantage during the middle quarters. Gwynn Park (13-11) converted just one field goal in the second quarter as the Scorpions broke the game open with an 18-4 run.

Seniors Lavon Long (11 points) and Dajuan Dent (12 points) were both strong inside offensively and helped protect the basket on the other end.

Though the outcome had long since been decided, the Oakland Mills students, some of whom began lining up outside the school nearly two hours before tip-off, still exploded onto the court to celebrate at the final whistle.

“We’ve been working for two weeks as hard as we can every day, looking forward to this game and it really paid off,” said Long, a Loyola (Md.) recruit. “There’s not much I can say because I assumed we would do this.”

Gwynn Park senior Jalen Harris scored 19 of his game-high 22 points in the final quarter.