"It was a huge game," Chapman said. "We hadn't really closed out on a good team so far this year, and that was our best game of the year, I think."
Chapman took control early, establishing himself in the post and leading the Royals on an 18-6 first-quarter surge that yielded a nine-point halftime lead.
Meanwhile, East star and Utah commit Parker Van Dyke had just five points in the first half, as the Royals focused on making the dynamic guard settle for contested shots.
Van Dyke finally started to find his stroke in the fourth, including a pair of 3s, and finished with 15 points. But East never cut the deficit below seven, as Chapman's presence seemed to alter the Leopards' potent offense.
East came into the game on a nine-game winning streak and had established itself as one of the top contenders in Class 4A. Chapman knew the matchup would be a measuring stick for the Royals (8-3), who were looking to vault themselves into the same tier as the Leopards and join the discussion of 4A's best teams.
"We're a team to be reckoned with," Chapman said. "We've [lost] close games with really good teams, but we had to close out against a good team like that."
It was also a chance for Chapman, a junior who has offers from BYU, Utah and a handful of other Pac-12 schools, to go head-to-head with Van Dyke, who came in averaging 27 points and guarded Chapman for much of the game.
"It was a little hyped up. It got me a little more competitive this game," Chapman said. "I could tell [Van Dyke] was a little more competitive, too."
O Roy's Brekkot Chapman, who has numerous Division I offers, leads the Royals past East's Parker Van Dyke, a Utah commit, and the Leopards.
• Roy jumps out to a 12-point lead after one quarter.