A Domino's Pizza employee who missed out on winning her second consecutive driver-of-the-year award has claimed the $15,000 prize was rigged and that the loss left her with a psychological injury.

Lynette Hart, a casual delivery driver at the Erina Domino's store in NSW, took her bid to overturn the result to the Fair Work Commission after she finished second in the 2016 competition to another driver.

Ms Hart was the winner of the 2015 award, which landed her a brand new car, and believed she was a good chance at winning two years in a row, the commission heard.

However, when she checked the standings in May 2016, Ms Hart noticed that her driver ranking had slipped by around 100 places.