PAST SEASON WINNERS ALI VINCENT AND MICHELLE AGUILAR GUEST STAR -- The contestants get a blast from the past this week with visits from season five winner Ali Vincent and season six winner Michelle Aguilar, both filling in as host while Alison Sweeney is on maternity leave. The contestants are also surprised by the arrival of some old friends, whose return promises to shake up the competition. And while one player is sidelined by medical issues, the rest compete in a balance and endurance challenge that finds each contestant standing on a platform, suspended six feet over a pool. One by one, the lines supporting the platform are removed, making it harder to stand, until only the winner is left standing. Later, Bob has last chance workouts at the beach before the weigh in, which is followed by a surprising elimination.