Sydney FC captain Luke Brattan has claimed he was punched by Central Coast Mariners striker Alou Kuol in an ill-tempered first leg of the two sides' A-League Men semi-final.

Losing 2-1 at home on Friday, Sydney face the unenviable trip to Gosford next Saturday, with a packed house expected to be on hand to try to propel the Mariners towards a second straight grand final.

Brattan knows his side are up against it for the return leg with defender Jack Rodwell and midfielder Corey Hollman both facing suspension, but the streetwise midfielder may have a few scores to settle with Kuol.

There was a coming together between the pair in the first half on Friday, and Brattan was ropeable when Kuol appeared to aim an off-the-ball jab to his midriff.

"He (Kuol) punched me in the stomach and apparently they looked at it (on VAR)," Brattan said.

"I'm not trying to get anyone sent off, but I grabbed his shirt and he punched me in the stomach.

"They looked at it and apparently it was nothing, that's no problem.

"The game isn't about referees, we didn't do what we had to do and we're 2-1 down.

"It is what it is, there's nothing in that."

Brattan's guile and leadership will be vital if Sydney are to salvage anything out of next week's trip to Gosford.

The absence of Rodwell, Hollman, star attacker Joe Lolley and an injury cloud over Jake Girdwood-Reich, who limped off with a quad complaint in Friday's loss, will test Sydney's depth.

"Our backs are against the wall with this, but we've got a great group and great coaching staff and they'll prepare us well," Brattan said.

"Whoever comes in will know their role and do a job. They're a fantastic team and they've won what they have for a reason.

"It's going to be a tough game, but it's definitely not over."