'Iron Boy' saves Sydney as Downey Jr tweets support

A seriously ill Australian boy was granted his wish on Thursday to become a superhero like Iron Man, with police staging an elaborate event on the Sydney Opera House steps as Hollywood star Robert Downey Jr tweeted his support.

Nine-year-old Domenic Pace, who has battled cystic fibrosis throughout his life, has long idolized Marvel superhero Iron Man and expressed his wish to be "Iron Boy", with the Make-A-Wish Foundation granted his dream to fight crime in Australia's biggest city.

In scenes reminiscent of Batkid - a five-year-old boy recovering from cancer who in 2013 became the diminutive version of the crime-fighter Batman in San Francisco - Sydneysiders turned out to watch Pace save the day on the harbor in a spectacle that took almost a year to organise.