This week starts off with a high-stakes pop challenge in which contestants race for the prize of immunity - and the winning team also gets three envelopes to give to the teams of their choice with instructions that could have a dramatic impact at this week's weigh in. Also, tensions are high between the trainers and one team suspected of game play, and a lifting competition rewards the winning team with a prize that everyone wants.

This week, contestants are surprised by the return of the blue and yellow teams, who were sent home after the first challenge of the season. Now they're back, 30 days later, to weigh in and try to earn a spot back on the ranch. Then a vigorous football challenge tests everyone's stamina, except for one player sidelined with medical issues, and provides immunity for the winner - but a big disadvantage for the losing team. Later, after another elimination round sends a player home, host Alison Sweeney surprises the contestants with exciting news.

It's a star-studded Olympic-themed episode of "The Biggest Loser: Couples" to help kick off the winter games! This week, the contestants head to Colorado to train like Olympic athletes at the U.S. Olympic training facility in Colorado Springs. Host Alison Sweeney tells them the game is going from teams to singles, and multiple medal-winning paralympic athlete Allison Jones warmly welcomes them to the U.S.O.C. campus. Trainers Bob Harper and Jillian Michaels invite two Olympians to help work out the contestants - gold medalist skier Julia Mancuso and Jeret "Speedy" Peterson, the freestyle skier famous for his "hurricane" jump. Then it's off to a pop challenge involving a slide board, where U.S. Olympic speed skater J.R. Celski cheers them on. Later, they engage in a biathlon challenge before moving on to this week's last chance workout -- with pairs figure skater Rockne Brubaker! Then their exciting week comes to an end as two more players are sent packing.