Bruce Jenner has promised his tell-all interview will be an ''emotional rollercoaster''.

The 'Keeping Up with the Kardashians' star's highly-anticipated chat with Diane Sawyer - in which he is expected to discuss his decision to transition to a woman - will air tomorrow (24.04.15) and network ABC has issued another teaser trailer ahead of the transmission.

In the short clip, Bruce said: ''It's going to be an emotional rollercoaster, but somehow I'm going to get through it.''

And later in the clip, the 65-year-old former Olympian admits he still has questions that need answering.

He added: ''I wanna know how this story ends, you know? How does my story end?''

The footage was the fourth excerpt ABC have released from the interview.

In an earlier clip, Bruce admitted his only concern during the transition will be his children Burt, 36, Casey, 34, Brandon, 33, Brody, 31, Kendall, 19 and Kylie, 17.

The reality TV star - who also has four stepchildren, Rob, 28, Khloe, 30, Kourtney 36 and 34-year-old Kim from his marriage to his now estranged wife Kris Jenner - said: ''I can't let myself hurt them. They're the only ones I'm concerned with.''

But he appears to have no regrets about his decision, adding: ''It made me who I am.''

In previous clips released from the two-hour long show, entitled 'Bruce Jenner: The Interview', he is also heard telling Diane: ''My whole life has been getting ready for this.''