Raucous chants of "O-Lym-Pic, O-Lym-Pic, O-Lym-Pic" echoed out of the jubilant Canberra FC dressing room after the team won 3-2 in extra-time in Sunday's fiery elimination semi-final at Deakin Stadium.

Olympic led 2-1 with eight minutes left in normal time, before Alex Oloriegbe equalised and Domenic Giampaolo struck the winner in the 97th minute.

Canberra FC moves on to a preliminary final showdown with league champions the Cooma Tigers next Saturday at McKellar Park, with the winner to face Belconnen United in the decider.

Emotions ran close to boiling point between the bitter rivals for the entire 120 minutes.

Canberra FC's Josip Jadric was yellow carded for abusive language towards Olympic supporters and his coach Andy Bernal was sent from the pitch late in the game for a verbal exchange with an opposition player.

But the sound of the Canberra players belting out the Olympic club name, while opening the door of their dressing room to make sure everyone heard it, did not sit well with Olympic coach Frank Cachia.

"It's a slap in the face and the boys aren't happy with that at all, but what are you going to do?" Cachia said.

"You only worry about what you can control."

Giampaolo said it was in response to Olympic's celebrations after its 4-2 win against Canberra FC in last week's final game of the regular season, which had no bearing on the finals.

"It's just a bit of banter because the (Olympic) boys love to sing their song even when it doesn't matter, so we give it back to them," Giampaolo said.

"The rivalry is on the pitch, best of mates off it, but we do love playing Olympic.

"It's the best fixture."

It's been a turbulent season for Canberra FC.

The most successful club in the ACT has been a shadow of its glory days, sacking coach Ray Junna mid-season and losing four straight games going into the finals.

"Especially after last weekend, it's been a rough season," Giampaolo said.

"Team morale's been a bit low and it does feel really good."

After Jadric put Canberra ahead in the 26th minute, Olympic responded with two spectacular goals, first to Callum Smith and then Mark Shields.

Smith's cracking volley was matched when Shields controlled the ball off his chest, spun and put it into the top corner to give the visitors a 2-1 lead at half-time.

They remained in the driver's seat until Oloriegbe equalised with eight minutes to go before Giampaolo made amends for missing a first-half penalty to score the winner.

For Olympic, it was a bitter pill to swallow after an impressive year to finish third on the table.

"It's hard to take when you're 2-1 up and let it slip," Cachia said.

"We started off this season with a new coach and have a lot of new players.

"I'm so proud to be associated with them."

CAPITAL FOOTBALL NPL

Elimination semi-final: Canberra FC 3 (Josip Jadric 26', Alex Oloriegbe 82', Domenic Giampaolo 97') bt Canberra Olympic 2 (Callum Smith 38', Mark Shields 45') at Deakin Stadium on Sunday.