From our every day heroes to our top sportsman and women – Australian athletes are all lining up to take their shot at the most difficult obstacle course in the world.

Heat 2 features the 'Battle of the Tradies', the only huband and wife team, Queenslander larrikin mates and a former elite gymnast from WA.

Tonight, 50 new competitors face the Ninja course. Three new obstacles make their debut in Heat 3: The Bomb Slider, The Cargo with Lache and The Ball and Chain.