While the future of their club remains uncertain, the Jets showed they were worth saving with a gutsy and determined performance to line up a home semi-final against premiers Melbourne City next weekend.

It was the club's first-ever finals win in 16 seasons of A-League Women and took almost three hours to secure after the the game was delayed for 20 minutes in the second half when the ground lights went out.

The sixth-placed Jets, who squeaked into the finals on goal difference, twice led before third-placed United had locked the score at 2-2 by the end of regulation time to send the game into 30 minutes of extra time.

Sarina Bolden opened Newcastle's account with the game just 11 minutes old, dancing around a defender on the edge of Western's 18-yard box and firing a shot into the bottom right corner of the net.

Jets goalkeeper Tiahna Robertson, in just her second A-League outing, produced a diving save in the 20th minute to deny Catherine Zimmerman, who also skewed a long-range shot wide of the goals in the opening stages.

But Alana Cerne found the first equaliser in the 23^rd minute with a back-post volley into the bottom left corner off a corner.

Zimmerman scored from a tight angle in the 40th minute only for it to be disallowed after the American forward was deemed to have tugged on defender Josie Wilson's shirt in her run to goal.

Five minutes later, Newcastle were back in front with Bolden driving a penalty shot into the top right corner after United defender Jaclyn Sawicki had handballed in the area.

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The Jets had the chance to extend the lead before the 56th-minute black-out when Emma Dundas delivered a pinpoint cross into United's goalmouth but an unmarked Lauren Allan could not make clean contact at the back post.

When play resumed after light was restored, the Jets were forced to withstand a mountain of pressure and did so with absolute desperation and a never-say-die resolve.

But United were granted the chance to square the ledger again in the 66^th minute when Libby Copus-Brown sent Zimmerman flying with a body check in the area and referee Georgia Ghirardello pointed to the spot.

Zimmerman calmly slotted into the bottom right corner to make it 2-2.

Jets coach Ryan Campbell provided an attacking injection with a triple substitution of Ayres, Hoban and Young Matildas striker Lara Gooch at the 70-minute mark.

In a surprise move, striker Milan Hammond had replaced Gooch for her first start of the season.

But the move paid dividends with Gooch, Ayres and Hoban providing the attacking spark the Jets needed when the game was sent into an additional half hour.

It took 11 minutes of extra time for Ayres to provide the breakthrough.

On her 25^th birthday, the lethal sharpshooter needed just one good chance and delivered when it was granted.

Mindy Barbieri's searching long ball found Ayres in acres of space in the box and the strike weapon needed just one touch to score with a left-footed shot into the bottom right corner.

Ayres then proved provided for Hoban to double the advantage in the 23^rd minute of extra-time with the 22-year-old's first A-League goal.

The Jets have only twice made finals - in 2008-09 and 2017-19 - but never progressed past their first game of the series.

They now play City, who the Jets have never beaten, in a two-legged, home-and-away semi-final.

City have elected to host the second leg and the Jets looks likely to play the first leg at Maitland Sportsground on April 21.

No.1 goalkeeper Izzy Nino will be available again after missing two games through suspension but 21-year-old Robertson, who was plucked from NPLW NSW two-and-a-half weeks ago as an injury replacement for Kiara Rochaix, has stated a case for her own inclusion with two impressive performances.

Central Coast Mariners face Melbourne Victory in the other elimination final on Sunday with the winner of their match meeting Sydney FC in the semi-finals.