Heart have accepted a bid for Socceroos defender Michael Marrone, who will miss Sunday's clash against Sydney FC to attend a medical with an unnamed Chinese Super League side believed to be Shanghai Shenxin.

The move comes as A-League rivals Central Coast Mariners prepare to lose as many as six players to cashed-up Asian and European teams in the January transfer period.

Mat Ryan's trial with Rangers is back on hold again after he pulled the plug until it's clearer what league the former Scottish giants will be playing in next season following a revamp of the Scottish league system.

But he is still believed to be chased by other clubs in Europe and could still leave before the end of the month.

"It happened to us pre-season when I accepted the job, I had Eli Babalj, Brendan Hamill and Curtis Good, and then within a month they're all gone," Aloisi said on Friday.

"It's something that you can't stop because they want to better themselves and Asia's got a lot of money, so if they come in and want to get a player, they can.

"It's a difficult situation for Australian football at the moment, but it gives opportunities for younger players to come through, so that's the positive side of it.

"The negative is that we keep on losing players, but as a coach I have to deal with it and get on with it and work with what I've got here."

Aloisi said Heart would continue promote talent from within, rather than turn their attention to the transfer period, which opens for A-League clubs on Monday.

"If something comes up that will interest us, then we'll look, but at the moment we're going to see how the young boys do," he said.

"We try and promote from within if someone's good enough, (but) we don't promote from within just for the sake of doing it.

"They have to be up to the level that we want them and if not, then we'll go and look elsewhere."

Aloisi said teenagers Jeremy Walker or Ersin Kaya could replace Marrone at right back, while Argentine midfielder Jonatan Germano also shapes as a potential stand-in.

"Jonatan can go back there but we're comfortable with him in the midfield at the moment, so we don't really want to shift him around," he added.

Sydney coach Frank Farina declared it was do or die for his charges against sixth-placed Heart at Allianz Stadium in their bid to climb off the bottom of the ladder.

"We know it's a must-win for them and that can also help us a little bit because they'll come all out and try and win the game and we might be able to pick a few holes when they leave themselves vulnerable at the back," Aloisi said.

"They've been a bit up and down since Frank's been there, but one thing they will do, they'll never lay down.

"They'll work hard for each other because they know that this is probably one of their last chances.

"If they want to make finals they need to start picking up points so they'll see this game as a must-win for them and that's why we have to be ready for it."