Merrick's contract was terminated on Monday after a run of four losses in five games left the Jets last on the ladder, six points adrift of the top six.

After two wins from their first 11 outings, Newcastle have 15 games remaining in which to turn their season around, starting with Friday's daunting clash against runaway leaders and defending champions Sydney FC at McDonald Jones Stadium.

Deans said reaching the play-offs was still a realistic goal and Newcastle's players should have the same mindset.

"Well if they don't [believe], that's a problem," Deans said. "The A-League is very quickly turned on its head. If you lose three or four games in a row, you drop from third or fourth to last.

"If you win three or four in a row, you go from last to fourth or fifth.

"So everybody that's out there is a fully aware of that. They've all been around the league long enough to know that it changes very quickly.

"It's just breaking the cycle of not winning that's going to be the challenge. The quicker we can do it, the better. Hopefully we can do it this weekend."

After his two training sessions, Deans said the attitude and enthusiasm of Newcastle's players indicated they were determined to make amends.

"I don't see a group of players who don't want to be here, or don't believe they're good enough," he said, adding that Merrick's unexpected departure would harden their resolve.

"You always get a reaction in situations like this, anyway, a positive one," Deans said.

"As a player, you obviously feel responsible in some way for a coach going ... as a team, when a coach gets sacked, it's your responsibility, because the coach is not on the field playing the game.

"I would imagine and I would hope that every player is feeling a little but hurt by it and take some responsibility for that fact the coach is gone.

"They need to lift because there's another coach coming in, and if they want to be a part of the new coach's plans then they need make sure that they're fully focused and performing."

Deans, who accepts that his caretaker role may last only a handful of games, said there was not much he could change strategically in such a short space of time.

"Obviously when you've lost three or four games in a row, you start to doubt yourself," he said.

"So it's more about just getting some self-belief back into the players and making sure they understand that there is enough quality there to be more than competitive in the game.

"But I don't think we need to make wholesale changes to style of play or anything like that."

For the time being, Deans will juggle his A-League duties with his regular jobs of coaching Newcastle's W-League team and their Academy.

His W-League assistant coach, Ashley Wilson, will sit in the hot seat for Friday's showdown with Adelaide.

"It's a great opportunity for her," Deans said.

Newcastle will be hoping to be boosted by the return of Panamanian striker Abdiel Arroyo against Sydney.

"It looks positive for him," Deans said. "We just have to see how he pulls up after today's session."

Playmaker Dimi Petratos, however, is nursing a groin problem and will have to prove his fitness at Thursday's training session.

A-League officials are understood to have discussed the prospect of deferring Friday's match if bushfire smoke creates hazardous air quality.