At the Augusta Civic Center, the Lakers built a 15-point halftime advantage on the way to a semifinal win over the Guardians.
Connor DiAngelo and Devin Boone propelled No. 1 Greenville (19-1) with 15 and 14 points, respectively. Nick Foley posted 10 points.
The Lakers take on No. 2 A.R. Gould of South Portland (17-3) in the South title game on Saturday at 2:45 p.m.
Caleb LaCroix and Sky Archer tossed in 14 points each for No. 5 Seacoast Christian of South Berwick.