'Grey's Anatomy': Watch the First 10 Minutes of the Alt Universe Episode, 'If/Then' (Video)

Grey's Anatomy Justin Chambers Ellen Pompeo: TV Still 2/2/12 - H
Vivian Zink/ABC

Meredith is Dr. Webber instead of Dr. Grey, Callie and Owen are married and have three kids, Derek and Bailey are punching bags for Chief Ellis Grey and that's just from the first 10 minutes of Thursday's Grey's Anatomy "If/Then" episode.

In an extended promo for the upcoming alternate universe -- which unspools after Meredith (Ellen Pompeo) drifts off to sleep as she ponders what her world would look like had her mother not had Alzheimer's -- Alex (Justin Chambers) and Meredith are engaged, Callie (Sara Ramirez) and Arizona (Jessica Capshaw) are at odds and April (Sarah Drew) is Mer's "person."

STORY: 'Grey's Anatomy's' Shonda Rhimes, Sara Ramirez Ponder Destiny in 'If/Then'

Also different: Meredith thinks Derek (Patrick Dempsey) is an "ass," Addison (Kate Walsh) is (finally!) pregnant and Owen (Kevin McKidd) -- still recovering from PTSD -- still Skypes with "his old buddy" Teddy (Kim Raver).

Oh, and everyone hates Cristina (Sandra Oh), while April is still pining for Charles (Robert Baker). Perhaps the biggest change, however, is that the opening credits now match Meredith's pink, preppy persona.

Check out the extended preview below. Grey's Anatomy's "If/Then" alternate universe episode airs Thursday at 9 p.m. on ABC. Will you watch?

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