The incident occurred in the 115th minute and just moments after Sydney FC retook the lead at Allianz Stadium last Tuesday night.

With the clock counting down, Marrone tried to retrieve the ball for a quick throw in, bundling over the youngster in the process.

An all-in brawl erupted, and the United man was shown a straight red while the ballboy was later welcomed up on stage for Sydney FC's medal presentation.

The Sky Blues won the match 2-1 in extra time, making a cleansweep of the trophies on offer in 2017.

Marrone was found guilty of "engaging in serious unsporting conduct" by the independent Disciplinary and Ethics Committee which also applied a suspended sanction of a further two A-League matches until the end of the season.

Conditions triggering the suspended sanction will be outlined in the Committee’s written judgement .

The 30-year-old old has already served the mandatory one match ban against Western Sydney Wanderers and will now miss Friday night's encounter with the Sky Blues.

He will next be eligible for selection in the away clash with Melbourne Victory on Friday December 8.

The player has seven days to appeal the decision.