In this Nov. 22, 2009 photo, Adam Lambert performs during the closing act of the 37th Annual American Music Awards in Los Angeles. Lambert is scheduled as the guest star on 'So You Think You Can Dance,' season finale airing Wednesday, Dec. 16, 2009. Producer Nigel Lythgoe said he's confident Lambert is going to be well-behaved.[Agencies]?

LOS ANGELES – "So You Think You Can Dance" producer Nigel Lythgoe won't predict which dancer will end up the winner on Wednesday's season finale. But he's confident that guest star Adam Lambert is going to be well-behaved.

Lythgoe said he passed the message to Lambert's camp that he doesn't expect any surprises during the live, two-hour episode, airing at 8 p.m. EST on Fox.

Lythgoe said he thinks Lambert may have enjoyed making a splash but will perform as rehearsed for "So You Think You Can Dance." Lambert was last season's "American Idol" runner-up to winner Kris Allen.

Other singers on the dance finale include Jennifer Lopez, Mary J. Blige and Leona Lewis, with performances by the Groovaloos dance group and by the show's top 20 contestants.

The finalists include husband-and-wife competitors Ashleigh and Ryan Di Lello along with Russell Ferguson, Jakob Karr, Kathryn McCormick and Ellenore Scott.

Viewers cast votes for the dancers after Tuesday's performance show. The winner revealed Wednesday receives a $250,000 cash prize.