The antonym for "are one back" could be "are ahead" or simply "lead." These terms suggest that someone or something is in a more advantageous position. In sports or competitions, being ahead often means having a higher score, faster time, or larger lead over opponents. In business, being ahead may indicate having achieved greater success or profitability compared to competitors. In personal life, being ahead can represent progress or achievement towards a particular goal. Alternatively, the opposite of "are one back" could be "are falling behind" or "trailing," indicating a disadvantaged position that may require extra effort to overcome.