The second-seeded Eagles (1-0) spent the first half trying to knock off the rust of the off-season as the first quarter ended in an 8-8 tie.
Eight turnovers in the second quarter allowed the seventh-seeded Patriots (0-1) to outscore the green and white 11-10 and take a 19-18 edge into halftime.
The Patriots extended their lead in the third quarter to three points (21-18, 23-20) on two occasions early in the third period.
The Eagles finally found positive traction when senior guard Cedric O'Hara buried a 3-pointer with 4:10 left in the third to give the Pierce City a 25-23 lead.
Colin Garner extended the advantage with a pair of triples, as the Eagles out scored East Newton 20-13 in the frame to take a 38-32 lead into the fourth quarter.
O'Hara finished the game with 10 points, all scored in the third period.
The stage was set for a dramatic finish in the fourth period but the game proved to be anticlimactic.
Pierce City stepped up the defensive pressure forcing East Newton into several empty possessions.
The Patriots only managed four points in the final eight minutes and didn't record the first of those points until there was 34 seconds left in the game.
"I thought we were a lot more aggressive in the second half," said Street. "We were able to drive the ball into their zone and that opened things up for us. The kids played with great intensity in the second half."
East Newton was led in scoring by sophomore Bryce Zimmerman with 14 points and Sam Swartz finished with 7 points.
Scoring for the Eagles were: Cody Fitchpatrick, 14 points; O'Hara, 10; Zack Hyde, 9; Garner, 8; and Kole Kelley, 4.
Pierce City will face Crane tonight in the semifinal. Tipoff is set for 7:30 p.m.