The 'unknown trainers' are finally revealed, and both will share their personal stories that led them to 'The Biggest Loser.' Their contestants, 'the unknowns,' confront one player they feel isn't working hard enough, and later, 'the unknowns' and the ranch contestants square off for a pop challenge. The winning player from each group will get a delicious healthy dinner prepared by Chef Curtis Stone, and compete for a coveted 2 lb. advantage at this week's weigh-in. Later, Dr. Huizenga gives 'the unknowns' startling news about their health, and one player is surprised to learn they have the highest percentage of body fat in the group. Meanwhile, trainers Bob Harper and Jillian Michaels single out a few of their contestants to find out what really led to their weight gain, and then the ranch contestants meet host Alison Sweeney for a water-carrying challenge that will give the winner the sole vote at this week's elimination. Later, a surprising weigh-in -- which results in shocking numbers for one team -- disappoints the trainers in a big way, leading to the elimination of one player they feel isn't ready to go home. Source: NBC