The Jets, who have only twice played finals since the competition's inception in 2008, had to beat Adelaide at Coopers Stadium on Friday night to stay in the finals race then rely on other results playing in their favour to secure a top-six spot.

They delivered on the first part, thumping the last-placed Reds and improving to 33 points.

The result put them onto level footing with Western Sydney and Melbourne Victory, who were also vying for one of the last two finals spots heading into round 22.

Newcastle's spot was confirmed on Saturday afternoon when Wanderers lost 2-0 to Wellington. Both recorded 10 wins in the season but the Jets had a superior goal difference.

Melbourne Victory stunned Sydney FC 4-0 at Leichhardt Oval on Sunday to move above the Jets and into fifth spot.

The elimination finals will be played April 12-14 with no games next weekend due to an international window.

The Jets will now meet third-placed Western United away in the first round.

Should they win their elimination final, Newcastle will play a home-and-away semi-final.

Six different players, not including leading scorer Sarina Bolden, found the back of the net against the Reds in a show of the Jets firepower heading into finals.

Newcastle led 3-0 at the break after captain Cassidy Davis, in her 150th appearance for the Jets, opened the scoring in the 27th minute then Lara Gooch (42nd minute) and Lauren Allan (47th minute) also found the back of the net.

Gooch made it a double two minutes into the second half before 16-year-old Emma Dundas (57th minute) scored her first A-League goal.

Melina Ayres bagged a brace off the bench, scoring in the 62nd and 70th minutes, then centre-back Alex Huynh completed the rout in stoppage time.

"I said to the girls at half-time, if we're going to be going into finals we want to make it that these teams do not want to play us," Jets coach Ryan Campbell said post-match on Friday night.

"I don't think any team that is preparing for a final is going to be excited to get to play us with the run we're on and the way we're scoring goals.

"The goals can come from everywhere. If we do get into finals, we're going to be a very hard team to beat."

At the heart of the performance, however, was replacement goalkeeper Tiahna Robertson.

The diminutive 21-year-old played a starring role on A-League debut, making several crucial saves before the floodgates opened.

Robertson was signed by the Jets on Thursday morning as an injury replacement with only 17-year-old Rookie Lily-Rose Dunbar available after Izzy Nino was red-carded then suspended for two matches for a scuffle with Victory's Emily Gielnik in round 21 and Kiara Rochaix sidelined following finger surgery.

The addition of Robertson, who came through the Jets Academy and was signed from University of NSW in NPLW NSW, proved a masterstroke.

She was composed and calm under pressure.

She tipped shots over the bar and around either posts at full stretch, came rushing off her line to deny Adelaide attacking raids with diving saves and plucked aerial threats out of thin air.

"Tiahna had an absolutely amazing game," Campbell said.

"She was very confident. She was on the front foot. She backed herself and she made some really key saves at good times, which was important.

"There's a good thing going in the group, the players and the coaches, everyone backs each other and that radiated onto the field."

It was the first time in the club's history that the Jets had won three games in a row.

Their two previous finals appearances came in 2008-09 and in 2017-18.