Carle determined to return

He's the $650,000-a-year investment who has spent just 543 minutes at the 'office' this year.

He's the $650,000-a-year investment who has spent just 543 minutes at the 'office' this year.

Now there are real concerns injury-prone Sydney FC marquee player Nicky Carle may not play again this season after suffering yet another setback.

A back injury will sideline the former Socceroo for at least four weeks, but there must be a question mark over whether he can return to full fitness before the season is out.

Carle started four of Sydney's first five games but has played just 102 minutes over the ensuing 10 rounds.

Worryingly for FC coach Vitezslav Lavicka, his prime assert last played a full game on September 4 before breaking down with a foot, toe and now back problems.

"I just want to be out there with the boys. I am a footballer so not playing hurts," Carle said.

"We have such a great bunch of blokes here so not to be out there with them week in, week out is really tough."

"I will be positive and stick to the program the club's staff will set out for me and come back from this."

But Lavicka looked less than optimistic after hearing the latest prognosis.

"It is bad news. We expected Nicky will be on the park soon but for now he is still unavailable," a glum Lavicka said before training on Thursday.

"No-one expected Nicky would have these problems but we need to solve it and give him time for the treatment."

"He is frustrated and everyone is frustrated but we need to be patient."

"He's a bit down but we are giving him support and trying to boost his confidence."

Striker Mark Bridge added: "There's not much you can say but 'keep your head up' but we've said that to him about four times this year and he's getting sick of it."

"People don-t understand how frustrating it would be for someone like him to come back with all this pressure and then get these unfortunate injuries."

"He's been unlucky this season. These are things that aren't in his control."

The Sky Blues head to Melbourne this weekend for a season-defining match against Heart at AAMI Park.

A win could take Sydney to within one point of the top six, just behind Heart, but a loss would open up a seven-point chasm.

"It's a massive game for us. If we win we're not that far off them but if they win they start to break away," Bridge pointed out.

"That top six is in close grasp at the moment and we don-t want to let that slip."