Question: Who most commonly sang the fastest-selling single by an Australian artist as a duet?
Sentence (from "Anthony Callea"): Anthony Cosmo Callea (born 13 December 1982) is an Australian singer-songwriter and stage actor of Italian descent (parents Santina and Cosmo) who rose to prominence after being the runner-up in the 2004 season of "Australian Idol".
Relevant evidence: No