The former Destiny's Child member turned solo artist called in as a guest mentor to The Voice Australia contestant Chris Sebastian before his semi-final performance. Sebastian's older brother, singer-songwriter Guy Sebastian, won the first Australian Idol in 2003 , and has served as a judge on Australian X-Factor and The Voice — including the current season. Chris Sebastian admitted to Rowland that he has felt as if he's always stood in the shadow of his older brother, a feeling to which Rowland said she could relate.