Nate Glidden converted a tough layup with 1.8 seconds left in overtime to provide the winning points as No. 6 Scarborough posted the first major upset of the Maine high school basketball tournament with a 59-58 win against No. 3 Gorham in a Class AA South boys’ basketball quarterfinal at a loud and packed gym at Gorham High.

Scarborough entered the tournament with a 6-12 record and had lost twice to Gorham by double-digit margins in the regular season. The Red Storm (7-12) will face the winner of Wednesday’s quarterfinal between No. 7 Sanford and No. 2 South Portland in the semifinals at 7 p.m. Feb. 23 at Cross Insurance Arena.

“For the past week I’ve told (my teammates) just ‘Believe, believe, believe,’” Glidden said. “I told these guys, the season didn’t go the way we wanted but … I know who we are, we knew who we were inside, and we came out here today and really proved it.”

De’Angelo Alston led all scorers with 22 points for Scarborough and made two clutch free throws with 1.9 seconds left in regulation to force overtime. Liam Garriepy added 14 before fouling out early in the fourth quarter.

Gabe Michaud scored 17 points for Gorham (13-6) with Ashton Leclerc (16) and Devin Dobson-Jacques (13) also hitting double figures.

CLASS C SOUTH GIRLS’ BASKETBALL

(4) HALL-DALE 71, (13) DIRIGO 39: The Bulldogs (15-4) jumped out to a 11-point halftime lead and never looked back on their way to a win over the Cougars (6-14) in a prelim in Farmingdale.

Hayden Madore led the Bulldogs with 17 points, while KJ Greenhalgh added 14 and Marie Benoit 12.

Jayce Brophy had 16 points and Grace Robbins 14 for Dirigo.

(5) RICHMOND 54, (12) MT. ABRAM 41: Izzy Stewart scored 12 of her 14 points in the second half to help the Bobcats (15-3) beat the Roadrunners (11-8) in Richmond.

Richmond advances to play No. 4 Hall-Dale in the quarterfinals.

Kara Briand added 15 points and 18 rebounds for Richmond.

(9) MADISON 56, (8) CARRABEC 53: MacKenzie Robbins scored 21 points as the Bulldogs (13-6) beat the Cobras (11-8) in a prelim game in North Anson.

Madison advances to play No. 1 North Yarmouth Academy in the quarterfinals.

Staff writer Steve Craig, Dave Dyer and Travis Barrett of the Kennebec Journal contributed to this report.