What a difference a week can make. Last night's live CBS broadcast of Big Brother 6 resulted in the eviction of Kaysar Ridha, the houseguest who only a week earlier had emerged as the upstart leader of the game's suddenly dominant alliance.

Kaysar had been nominated for eviction by Maggie Ausburn, Big Brother 6's fourth Head of Household. As last week's Head of Household, Kaysar had engineered the eviction of Eric Littman, Maggie's one-time "secret partner" in the competition. After surviving Kaysar's plan to ensure Eric's eviction by nominating both her and Eric for eviction, Maggie proceeded to win the Head of Household competition that occurred immediately after Eric's ouster.

Given the opportunity to quickly avenge Eric's eviction, Maggie had initially nominated Kaysar and James Rhine, the houseguest who had betrayed Eric and conspired with Kaysar in order to save himself from eviction, for eviction. However Sarah Hrejsa, James' girlfriend, proceeded to win the week's Power of Veto competition, enabling her to both save James from the chopping block and ensure that she herself wouldn't take his place. With James no longer up for nomination, Maggie had nominated Janelle Pierzina, Kaysar's closest ally in the house, to take James' place.

Despite a last-ditch effort to convince Maggie to keep him in the house, the Big Brother 6 houseguests voted Kaysar out of the house in a 7-1 vote, making him the fourth houseguest to be eliminated from the summer-long reality competition.

After Kaysar's eviction, the remaining houseguests competed in an alliance-exposing "Eliminator" Head of Household competition similar to Survivor's now legendary "Coconut Chop" challenge. With the disembodied voice of Big Brother hostess Julie Chen firing trivia questions at them from her nearby studio set, the houseguests competed to be the first person to correctly answer questions about their previous activities in the house. After each correct answer, the houseguest who supplied it was allowed to eliminate one of the other remaining houseguests from the competition.

Predictably, the competition did not go well for Maggie and her group of largely passive allies (as the outgoing Head of Household, Maggie was unable to compete in the challenge.) One by one, Jennifer Vasquez, Ivette Corredero, Beau Beasley, and April Lewis were eliminated, with Kaysar allies Sarah, Rachel Plencner, and Howie Gordon emerging as the challenge's final three competitors. After Rachel correctly answered a question and eliminated Sarah, Howie correctly answered the next question and was forced to eliminate his own one-time "secret" partner, making him Big Brother 6's fifth Head of Household.

However, although the HoH competition was over, Big Brother's Thursday broadcast wasn't, with Julie surprising the houseguests with an announcement that as part of the show's "Summer of Secrets" theme, the competition would be taking another twist.

Unbeknownst to the houseguests, the first four contestants evicted from the Big Brother house had not returned to their homes and had instead remained cut off from the outside world and sequestered in separate locations. As part of this season's launch of the show's "America's Choice" viewer voting polls that typically allow Big Brother fans to award relatively minor rewards to their favorite houseguests, CBS will allow the show's audience to determine which one of the previously evicted houseguests will be allowed to return to the house. However, since Ashlea Evans (the first evicted houseguest) left sequester due to undisclosed reasons, Big Brother 6 viewers will only get to choose between the show's three most recent evictees: Kaysar, Eric, and Michael Donnellan (Kaysar's one-time "secret" partner.)

Beginning immediately after last night's broadcast, CBS began allowing viewers to cast their votes online at CBS.com or via cell phone text messaging. The voting will close on Wednesday, August 10 at 3PM ET. Julie will reveal the identity of the "America's Choice" winner during Big Brother's live broadcast on Thursday, August 11, after which the lucky evicted houseguest will immediately return to the game.

Text message voting is only open to U.S. residents and will carry a cost of $0.49 per text message plus applicable taxes. Other restrictions on voting may apply.