Olympic started with a bang and finished with a boom to advance to the National Premier League decider against Belconnen United at McKellar Park next weekend.

An early Nathan Megic strike put Olympic in front and they never relinquished the lead against Gungahlin United in a 2-0 preliminary final win at Deakin Stadium on Saturday.

Olympic are gunning for a second consecutive treble and will look to seal a perfect season against Belconnen in the decider and win a third straight grand final.

If beating Olympic was supposed to be like climbing Mount Everest, the first two minutes meant Gungahlin needed to overcome an avalanche in the early stages of their trek.

Megic scored inside three minutes for Olympic to put the favourites in the box seat to secure another grand final appearance before Stephen Domenici put the icing on the cake in the dying moments.

He hadn't scored a goal all year but Megic struck when it counted in the absence of Nic Bobolas, who was helped from the field in the major semi-final.

It was their third game in eight days after playing a friendly against A-League club Newcastle but Olympic showed no signs of slowing down in the hunt for more silverware.

"I got asked the question whether or not it was smart with the timing of it all [the Newcastle game], but you don't get to dictate to A-League sides when you're going to play," Cachia said.

"The only thing we could say was whether it was going to be a Tuesday or a Wednesday so we picked the Tuesday in case we did need to play this weekend. That's what happened.

"I said to the guys, if we did go down we weren't going to use Tuesday as an excuse."

No excuses were needed when the league's leading goal scorer Domenici put the result beyond doubt in the 92nd minute when he beat the goalkeeper in a one-on-one situation.

Gungahlin came back from the brink of extinction to go close to a grand final appearance and Cachia praised the work of rival coach Marcial Munoz for building the club to what it is today.

"Hats off to them. What Marcial has done with them has been outstanding," Cachia said.

"They've got a good foundation to build on for future seasons. What they probably saw is that's how you actually build some sort of culture at a club.

"Instead of just throwing a lot of money behind players and trying to get some sort of dream team, he's built a squad of boys that will play for each other and play for him.

"Look at the results, [for over 90 minutes] they were one goal away from a grand final."

Belconnen await the defending champions having booked their ticket to the grand final in a thrilling penalty shootout win over Olympic in the major semi-final.

AT A GLANCE

Capital Football NPL: CANBERRA OLYMPIC 2 (Nathan Megic '3, Stephen Domenici '90+2) bt GUNGAHLIN UNITED 0 at Deakin Stadium.

CAPITAL FOOTBALL NPL GRAND FINAL

Saturday: Belconnen United v Canberra Olympic at McKellar Park, 4.30pm.