After conceding three goals in the opening 22 minutes, United skipper Ash Sykes led the fightback to ensure the visitors earned a vital point from the eight-goal thriller in Western Australia on Saturday night.

A Sam Kerr masterclass proved the difference in the first half as the Matildas superstar netted a hat-trick inside 35 minutes, but Canberra found a way to claw their way back.

Leading into the contest United vowed to shut down Kerr but the world's best player was simply unstoppable in the opening 45 minutes in Bunbury.

It marked Canberra's toughest road trip of the year after flying to Perth then driving two hours south to play in the coastal town and the visitors struggled early with the high-tempo and 30-degree heat.

Perth set a ferocious pace and Kerr opened her account with a sharp finish on 13 minutes thanks to a pinpoint through ball from American import Rachell Hill.

Three minutes later and the Glory skipper had a double after Clare Hunt failed to clear and Kerr pounced to poke home past United goalkeeper Haley Kopmeyer.

It was turning into the road trip from hell when Kerr turned provider and Hill nailed the third inside the box on 22 minutes, but Sykes immediately launched the comeback with a goal 60 seconds later.

Canberra striker Elise Thorsnes found the side netting from a free kick on the edge of the box, before Sykes hit her brace after digging out a loose ball from the corner to hammer home on 34 minutes.

Sykes almost had her a hat-trick two minutes but her shot flew just wide of the far post and Kopmeyer began to find her feet with back to back saves.

Just as the visitors looked to be working their way back into the contest Kerr struck again after Hill's pass split the defence to leave Kopmeyer no chance.

An unbelievable seventh first-half goal arrived just before the break when Grace Maher's free kick proved too strong for Perth shot-stopper Melissa Maizels.

The contest showed no signs of slowing down in the second stanza with several spectacular saves at both ends, before Thorsnes found the equaliser.

Englishwoman Laura Bassett delivered a pinpoint cross from a free kick and when Perth failed to clear Thorsnes smashed the loose ball into the back of the net with half an hour to play.

The speed dropped off briefly as the players began to feel the heat, before a frantic final 15 minutes produced heroic saves from Kopmeyer and Maizels.

Thorsnes and Hill both had chances to win it as tempers flared in a fiery five minutes of additional time, but in the end the sides couldn't be separated and were forced to share the spoils.

Canberra have not missed finals since 2012 and with two games remaining they still control their own destiny after the draw put them in fourth place on goal difference.

They face third-placed Newcastle and ladder-leaders Brisbane in the final two rounds and two wins could secure United a home semi-final.

AT A GLANCE:

Canberra 4 (Sykes 23' 34' Maher 45' Thorsnes 61') drew Perth Glory 4 (Kerr 13' 16' 42' Hill 22')