The bout on April 27 will be Khan's first contest in Britain for two years but Diaz believes that he has the quality to beat his younger opponent.
"I'm looking forward to it and very excited," the 33-year-old told Sky Sports News. "They think it's a safe fight, for him [Khan] to come back and rebuild his career and his confidence.
"I'm going to the UK for a victory and I will get that knockout. This is a big opportunity for me so I'm training like never before to make sure everything is right.
"My head is clear, my personal life is good and this is a great time for me to be fighting."
Diaz has suffered seven losses in a 48-fight career.