American Fork (16-2, 7-1), which entered the game ranked No. 3 in The Tribune's rankings, used a 7-0 run to end the second quarter and went into the locker room with a 31-24 lead over the Knights (16-3, 7-1), the top-ranked team in Class 5A.
The Cavemen drew even more momentum to open the third quarter when senior Zac Hunter found himself wide open for a slam dunk that brought the standing-room-only crowd to its feet.
"We had a play set, and we executed it perfectly," said Hunter, who finished with a game-high 19 points. "We went out and gave 110 percent, and it feels good."
Lone Peak's Nick Emery scored just 10 points, well below his state-leading average of 23. Emery drew a personal foul and then a technical for grabbing American Fork's Austin Waddoups with 48 seconds left in the third quarter.
The technical foul was Emery's fifth personal and kept him off the floor for the final period.
"Anytime Emery is not on the floor, it's good for us and I think that was a turning point," said Meacham. "The refs were letting them play, and sometimes in competition guys get into it. We were able to keep our heads in the game."
Without Emery, Lone Peak relied on T.J. Haws, who scored five straight fourth-quarter points, which cut the lead to one with just more than a minute to play. Hunter answered with a hard-fought layup, and the Knights were unable to get any closer.
"We learned from the mistakes we made the last time we played them," said Mecham of Lone Peak's 55-40 win on Jan. 20. "It was a fun celebration in the locker room, and we will look to keep this momentum."
American Fork will next be in action against Bingham, while Lone Peak will look to rebound against Lehi on Friday.
Boys' basketball American Fork 58, Lone Peak 50
R American Fork snaps a 12-game losing streak to rival Lone Peak.
• The Cavemen are still in the race for the Region 4 title, which would be their first region title since 2005.
• Lone Peak's Nick Emery leaves the game after picking up a technical foul late in the third quarter.