McCoy was named Player of the Game despite a scoreless first quarter. He had 10 of his game-high 20 points in the second quarter and helped Sierra Canyon reclaim a lead after trailing 12-7 at the end of the first eight minutes.
Sierra Canyon is in the driver's seat at 5-0 in Mission League play with one week remaining in the regular season.
Martinsen scored 12 of his 16 points in the second half to help spark the Trailblazers. Sierra Canyon held Harvard-Westlake's leading scorer and Texas signee
Joe Sterling to just five points on 1 of 7 shooting.

Sierra Canyon's Brandon McCoy (0) drives on Harvard-Westlake's Joe Sterling on his way to a game-high 20 points to help the No. 3 Trailblazers to a 55-47 victory on Wednesday night. (PHOTO CREDIT: Jace Kessler)
Georgia State signee
Amir Jones scored nine points in the first quarter to lead Harvard-Westlake's early surge. After Sterling picked up his third foul midway through the second quarter, Sierra Canyon made its move.
McCoy turned defense into offense with a steal and dunk to bring Sierra Canyon within three. Moments later, he hit back-to-back threes to give the Trailblazers their first lead of the game at 21-18.
Sierra Canyon outscored the Wolverines 18-9 in the second quarter to take a 25-21 lead into the intermission.
Staying hot in the third quarter, McCoy produced another big dunk coming off of a blocked 3-point attempt from Sterling. Sierra Canyon extended its lead to double-digits midway through the quarter.
Dominique Bentho scored seven points late in the third to cut the deficit to just three with 1:30 to play, but Martinsen knocked down a pair of free throws to maintain Sierra Canyon's lead at 41-33 after three quarters.
McCoy and Martinsen combined for 11 points in the fourth quarter and the North Carolina pledge Adams, on his 18th birthday, picked up an offensive rebound and put-back for an and-one that gave the Trailblazers their biggest lead of the game at 12 points with under two minutes to play.
Bentho had 11 points and
Pierce Thompson pitched in 14 to lead the Wolverines (21-3, 4-1 Mission League).
Sierra Canyon (19-1, 5-0 Mission League) is now 5-0 against teams currently ranked in the top 100. The Wolverines, meanwhile, are 0-2 against current top 100 teams.
Sierra Canyon hopes to repeat as a state champion after going 27-7 and raising the Division I crown a year ago. Harvard-Westlake went 31-3 last year, losing in the state's Open Division quarterfinals to eventual state champion
Roosevelt (Eastvale).