In anticipation of Bruce Jenner's explosive sit-down with Diane Sawyer, we're looking back at how much the father-of-six has changed over the past year-and-a-half.

Rumors the Olympian wanted to transition into a woman began in Decemember 2013 when the former athlete had a "tracheal shave" — which is a surgical procedure that flattens the Adam’s apple. From there, he's been spotted with a longer hairdo, fresh manicures and allegedly even got breast implants.

He has yet to comment on the reports — and his family has also tiptoed around the subject. But earlier today, his youngest daughter, Kylie Jenner, 17, shared her support for his upcoming interview by posting the following picture and message on her Instagram account:

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daddy throwback. #Tonight #DianeSawyer #ABC #love

A post shared by Kylie (@kyliejenner) on

Bruce Jenner: The Interview airs at 9 p.m. on ABC. Scroll through to see his transformation.