Wladimir Klitschko admits losing his world titles to Tyson Fury still stings, although he is more determined than ever to regain them.
Fury took possession of the Ukranian's WBA, WBO and IBF titles after claiming a unanimous points decision in Dusseldorf in November.
Klitschko has had time reflect on his defeat, and said: "For the first time in so long, I had to experience the feeling of stepping out of the ring as a loser. That was very disappointing for me; I suffered day and night after the fight and I am still suffering.
"I have decided to seek a rematch against Fury. I want to show that I have much more to offer, and I want to overcome this challenge. I could not realise my potential during the last fight, and I want to, and will, change this in the return match.
"Moreover, I know: A lost fight does not mean I have lost the war. 'Failure is not an option,' I tell myself and my team repeatedly. But if you have suffered a failure, you shouldn't lick your wounds for too long. Keep going!
"This is exactly the same thing I tell businessmen and managers: A defeat is painful, oh yes it is, but it is something you learn from and keep going. To become better.
"Eleven years ago, I turned everything that characterised me as a sportsperson upside down. My training, my diet and my team. This was the result of a thorough analysis of my defeat: What mistakes did I make? What conclusions did I arrive at?
"That took a bit of time and honesty. I am going to take exactly the same approach this time as well. I am rising to the challenge, not only for the return match, but the longer path forward, which will be hard, because I scrutinise everything."