The fourth-seeded Cougars dropped a point at No. 1 singles but were perfect the rest of the way in advancing to the Class A North semifinals against undefeated top seed Camden Hills on Saturday.
Mick Gurney and Zach Gunther won their matches at No. 2 and No. 3 singles, respectively, in straight sets for Mt. Blue (9-4). Ryan Haszko and Aubrey Hoes were 6-4, 6-2 winners over Nick DaRosa and Kian Murray.
Connor Shaw was the lone victor for No. 5 Brunswick (8-5), with a 6-4, 6-2 victory over Chris Marshall in first singles play.