'Dancing With the Stars' Casts First Former 'Idol' Contestant Ever!

2/24/2013 1:50 PM PST

'Dancing With the Stars' Casts First Former 'American Idol' Contestant Ever!

The two biggest reality shows on the planet are about to come together -- TMZ has learned the identity of four of the contestants for this season of "Dancing With the Stars" ... including the first ever former "American Idol" wannabe.

"DWTS" has not revealed their cast for the upcoming season yet ... but sources close to the show tell TMZ that Kellie Pickler -- everyone's favorite country bumpkin from season five of "Idol" -- will be doing this season of "DWTS."

In addition to Pickler, our sources say country star Wynonna Judd, "Bachelor" star Sean Lowe and 2012 Olympic gold medal winning gymnast Aly Raisman are among this year's cast.

Not that TMZ condones gambling, but put $20 down on Raisman -- three former Olympians have won the show in the past. You're welcome.

A rep for the show tells TMZ, "We do not comment on casting rumors, but tune in to 'GMA' on Tuesday when we reveal the cast live!"