American Swimmer Michael Phelps says he is ready for another Olympic challenge.

After suffered defeats at the past two world championships he says he has learned from his mistakes.

(SOUNDBITE) (English) MICHAEL PHELPS SAYING:

"I don't know how you can really be afraid of failing. I guess I have failed a lot over the last couple of years. I guess leading up to this point it is kind of, my career is kind of been a joke - I guess since Beijing. I guess you learn from everything. I prepared myself the best way that I think that we can and I am going to step up on the block on Saturday and race as hard as I can."

The 27 year-old Phelps, who holds the Olympic record for Gold winning eight gold medals -- says he is ready to retire after the London Games.

(SOUNDBITE) (English) MICHAEL PHELPS SAYING:

"It is just not! I knew I wanted to swim for another four years after 2008 and I don't have that feeling now. Sure I am excited, I am at the Olympics, I am representing my country but I just don't see myself going on. I don't know what it is, I don't know why, I can't go into detail but I just don't want to."

The American swim team heads into the Olympics boasting the fastest times this year in 12 of the 26 individual events.

Deborah Lutterbeck, Reuters.