A 107th-minute goal to Melbourne City's Jessica Fishlock from a corner saw a stunned silence fall over Canberra Stadium as the visitors booked their ticket to the grand final against Perth Glory.

A championship victory loomed as the perfect way to go out for the Canberra mentor after she made the decision to return to Queensland at the end of the season.

The move hasn't come as a shock to those around the club, with the players and staff already well aware Dower was on her way out, with a return home allowing her to be closer to family.

Dower joined Canberra United as an assistant coach ahead of the 2013-14 season and has been in the top job for two years for two semi-final appearances.

Canberra would have hosted the grand final had they beaten City, but instead will be left to rue what might have been.

As lightning struck around Canberra Stadium, Fishlock ensured it would strike twice on the paddock after United were knocked out in the corresponding fixture last season.

City looked certain to have scored a winner through Fishlock 10 minutes into extra-time but the slightest of touches from United goalkeeper Trudy Burke deflected the ball into the crossbar.

While Fishlock was denied on that occasion, it wouldn't be too long until she had the winner.

The match was the second for both sides at the venue this season after their round one meeting, and 5072 turned out across the A-League and W-League double header.

Canberra United made its intentions clear right from the opening whistle and registered 22 shots to Melbourne's 14, but neither side could convert until deep in extra-time.

A young Canberra outfit could have done with the big-match experience of co-captain Michelle Heyman, but the Matildas star has been out of action with injury for the back end of the season.

United went close to scoring first but former teammate Lydia Williams scrambled in the last line of defence to deny a flurry of shots from Emma Checker and Celeste Boureille.

With less than 13 minutes left on the clock and neither side able to break the deadlock Dower told stars Ellie Brush and Lisa De Vanna to warm up, much to the delight of the Canberra crowd.

Off came Grace Maher and Jasmyne Spencer, and two of the competition's biggest names took to the field looking to turn the game on its head.

Chances were hard to come by in the second stanza but De Vanna was in the centre of the action when she came onto the field, setting Ochs up for a shot spilled and regathered by Williams.

De Vanna looked like she might find a way through the City defence in the dying stages as Canberra pressed for a winner, but it didn't come as referee Rebecca Durcau signalled an end to regulation time.

MELBOURNE CITY 1 (Jessica Fishlock 107m) bt CANBERRA UNITED 0 at Canberra Stadium on Sunday night. Crowd: 5072.