It was an explosive maiden century from Jett Hopper on Wednesday that gifted HCA passage into the semi-final against Colac.

Elsewhere, Wimmera-Mallee's Aaron Schofield earned his place in the centurion's club with an unbeaten knock that wasn't enough in a 35-run semi-final loss to Warrnambool Blue.

HCA took to the field for Thursday's semi-final buoyed by a feat of individual brilliance the previous day.

Hopper's dominant century handed his side a 114-run win against Portland on Wednesday.

HCA's captain took Portland's bowling attack to task from ball one, crafting his way to an undefeated 144.

Coach Simon Hopper described the innings as one of the best the country week carnival had ever witnessed.

"I made a comment to the group between innings that it was probably the best individual junior innings that I've seen from anyone," Simon Hopper said.

"He hits the ball really hard and hits through good regions, through cover and over cover, and he hits straight well. When he gets going, he's good to watch.

"At that age, he's still only 14, it's pretty impressive."

Cricket's cruel nature would catch up with Hopper in the semi-final, who was dismissed for a duck in the second over.

William Drummond shouldered the batting efforts and composed a hard-fought 73 against a skilled bowling unit.

Late Logan Millar (21) fireworks saw the hosts post 150.

HCA snuck in two quick wickets, but Colac started to build a chase until opening bowler John Officer returned to the attack.

Officer claimed three scalps in one over to have Colac 5-96, swinging momentum back in his side's favour.

It was Connor Weidemann who would wrap the game up, taking the final two wickets on his way to figures of 3-9 at an economy rate of 1.28.

HCA face Warrnambool Blue in the final on Friday morning.

A herculean performance from Wimmera-Mallee Cricket Association's Aaron Schofield on Thursday was not quite enough to carry the side to the under-15 country week grand final.

Schofield reached triple figures with the last ball of the innings against Warrnambool Blue, finishing on 100 not out to cap a memorable semi-final performance.

Schofield however could not find a batting partner during his innings, as no other Wimmera-Mallee teammate reached double figures. The side finished at 9-149 after 40 overs, 35 runs short of Warrnambool Blue's 6-184.

Warrnambool Blue were guided by Flynn Wilkinson (44), Aidan Forsyth (39) and Harry Schrama (33) to the impressive total. Wilkinson also took 3-27 with the ball to help his side to a grand final.

Wimmera-Mallee had booked its place in the semi-finals with a strong 72-run victory against Warrnambool Gold on Wednesday.

Will Deason (41) and Schofield (48) helped the side post an imposing 207, before Patrick Sheahan (3-15) contributed with the ball to help them secure a top-four position.