In the end, unless you are Sydney FC, injuries and setbacks will affect your season.

Perth kept their A-League finals hopes alive with the win on Friday night at McDonald Jones Stadium, which came from a Diego Castro penalty and an Adam Taggart finish.

Glory, though, with a round to play, are scrambling to snatch a finals spot after an inconsistent season.

Newcastle will finish second and host a semi-final in week two of the finals.

But after three consecutive losses, their fairytale rise from wooden spooners to contenders has plateaued.

Merrick, content to keep faith with his side before the Perth defeat, was livid post game saying of possible changes: "I'm not putting that side out again."

If their form doesn't turn around the Jets' return to finals soccer may be short lived.

"We've got two more games left and the way we're playing, that will be it, finished," Merrick said.

"We won't be playing in a grand final, if we're going to play like that, and the sooner the boys get that message the better.

"But we're not improving. If anything, we're getting worse.

"There's obviously some boys feeling under pressure.

"If they play like that in a finals match, it's going to be embarrassing."

The Jets round off their regular season campaign against the second-bottom Central Coast Mariners.

Lowe, pleased with his side's recent turnaround with key men available again, compared Perth's earlier injury troubles with the Jets' current woes.

"It was probably a bit like Newcastle now," Lowe said.

"They've lost the lad up front who's been super for them, (Andrew) Nabbout, the captain (Nigel Boogaard) is out, you've got (Roy) O'Donovan coming back after a little bit of an injury, you've got the two foreign boys (Ronny Vargas and Pato Rodriguez) who are not quite there, and once that happens, it doesn't matter who you are, you get affected.

"Such is life.

"If you don't, like Sydney and you've got quality players, you fly through the season. It's about getting your quality players on the park."

The Jets' worries deepened with Vargas (groin) and Wayne Brown (calf) coming off with injuries against Perth.

Merrick said defender Daniel Georgievski would be back from suspension, before seemingly joking about an early return for injured skipper Boogaard.

"We might have to play big Nigel as well ... if you get him hopping on one leg, he's pretty good," he said.

"I don't know about that, but there will be a couple of new players in the team next week; that's for sure."

Australian Associated Press