Sydney FC is up in arms about the proposed rebranding of Melbourne Heart in line with the club owners Manchester City, protesting that there is only room for one A-League team playing in sky blue.
Twice champions Sydney have played in sky blue, the state colour of New South Wales, for 10 years, while Heart have played in red and white stripes since they entered the league in 2010.
Manchester City led the consortium which bought Heart in January and are expected to change the club's name after registering the business name Melbourne City FC with the local authorities.
The English Premier League club last year established New York City Football Club, who will play in sky blue when they enter the Major League Soccer competition next year, and Melbourne are expected to follow suit.
The Sydney FC chairman, Scott Barlow, says in a 10-team competition the idea of two teams wearing sky blue is nonsensical.
Football Federation Australia would have to approve the rebranding of Melbourne Heart.