"This has been our goal all season," Scotties head coach B.J. Smith said. "Now our goal is one more win."
Highland held a narrow two-point lead inside a minute left in regulation when sophomore Ryann Bowser delivered the knock out blow. Bowser hit her second three of the contest to put the game out of reach. She finished with a game-high 23 points, eight rebounds and five steals.
Julia Alves added 17 points on 6-11 shooting and nine rebounds for HCC.
Highland and SCC were knotted 33-33 at halftime, but HCC slowed St. Clair's offense in the second half allowing them to shoot just 28.6-percent and forcing 22 total turnovers.
The Scotties have now won 16 of their last 17 games.
HCC will meet No. 4 Mesa CC in the championship Saturday at 7:30pm. Mesa reached the title game after upsetting No. 1 North Iowa 85-73 on Friday.