NBC has announced that the third edition of its The Biggest Loser reality weight loss competition will debut on Wednesday, September 20 at 8PM ET/PT with a special two-hour premiere.

Although regularly scheduled to air in the Wednesdays at 9PM ET/PT time period, The Biggest Loser 3 -- which will feature the introduction of new The Biggest Loser trainer Kim Lyons -- will air special two-hour 8-10PM editions for each of its first two weeks. After two weeks, the show will resume its normal one-hour format and begin airing Wednesdays at 9PM effective October 4.

As a result of The Biggest Loser's two initial double-size broadcasts, Twenty Good Years and 30 Rock, two new NBC sitcoms scheduled to air in the 8-9PM proceeding The Biggest Loser, won't premiere until later in October. Twenty Good Years will premiere with back-to-back episodes on October 4, with 30 Rock premiering the following week on October 11 at 8:30-9PM ET/PT.

NBC's decision to premiere The Biggest Loser 3 with two double-sized 8-10PM episodes also means that despite its late May decision to move the show back an hour from its originally announced Wednesdays at 8PM time period, The Biggest Loser 3's first two episodes will still end up facing off against ABC's smash-hit Dancing with the Stars reality show.

Earlier this week, ABC announced that Dancing with the Stars 3 will premiere on Tuesday, September 12 at 8PM ET/PT with a special two-hour premiere. Its first hour-long results show will air the following night in the show's new Wednesdays at 8PM regular time period.