The 2015/16 A-League Golden Boot winner had to be replaced late in the first half of City's 3-2 FFA Cup win over Hakoah Sydney City on Tuesday night after a heavy tackle.

Fornaroli left the venue in a taxi for X-rays which have revealed bad news for the title hopefuls which threaten his availability for the start of the new season which commences in October.

In a club statement, City confirmed Fornaroli had suffered a fracture to his right ankle.

Fornaroli will undergo surgery in the coming days, although the club declined to disclose an estimated period of absence.

The Uruguayan has scored 49 goals in 66 appearances for City in all competitions since joining in 2015.