Spoiler alert!

As Oprah Winfrey prepares to end her 25 year run on The Oprah Winfrey Show May 25, Us Weekly is taking you behind the scenes for Surprise Oprah! A Farewell Spectacular, two star-studded hours that will air as her second and third-to-last shows.

While the guest list and show details have been kept top secret -- even from Winfrey, who is not a fan of surprises! -- until the taping begins, there's one thing we know for sure: There'll be lots of happy tears and even more a-ha moments.

PHOTOS: Revisit Oprah's legendary career

Watch this space Tuesday night as Us Weekly's Allison Corneau offers real-time updates on all the A-listers attending the one night only event at Chicago's United Center. And for even more Oprah, don't forget to follow Us on Twitter (@usweekly) to get scoop, photos and tidbits you won't see on TV.

Tell Us: What is your all-time favorite Oprah Show moment?

Get more Us! Follow us on Twitter, Friend us on Facebook, Subscribe to Us Weekly