Amir Khan believes the unheralded Lamont Peterson poses a bigger threat to his two light-welterweight titles than former champion Zab Judah did.
Khan defends his WBA and IBF belts when he faces hometown challenger Peterson in Washington on Saturday.
In July, Khan knocked out Judah to add the IBF title to his WBA belt.
"I definitely think this will be a tougher fight than Zab Judah was," Khan said. "He's one of the most dangerous opponents in the division."
The 24-year-old, who knocked out Judah in the fifth round in Las Vegas, feels that Peterson has shown character in earning another shot at the title after losing a clear points decision to WBO light-welterweight champion Timothy Bradley in 2009.
In his three fights since then, Peterson has won two and got up off the canvas to draw against Victor Ortiz last year.
"At the end of the day you have to remember that while Peterson might not be one of the biggest names, he's one of the most dangerous opponents in the division," Khan said.
"He's been in the top 10 for a long, long time. He's had some big fights and has only lost once.
"He's the number one contender for my IBF title. It just shows that he's a tough character, and he'll be up for this fight because it's a massive opportunity for him."
The Bolton fighter accepts that the American crowd will makes his task more difficult against a boxer with a 29-1-1 record (15 KOs), but is confident he has the experience to prevail.
"Me and my trainer Freddie Roach know what to do," he said.
"We're fighting in his home city which will give him more motivation and more confidence against me, and we know he's tough so we can't take this easy.
"I take every fight seriously and that includes this one."
Peterson, who has admitted in the past to losing focus in the ring during the big fights, believes he now has the temperament to win titles.
"I've been getting more comfortable at that elite level by just fighting in these big fights, in world level fights, and by just being more confident about doing what I know I can do," he said.
"Going into big fights, my mind is racing. I want to be perfect. I want to do everything right and I seem to overdo a lot of things instead of just being me.
"At this point, though, I feel comfortable enough to be me. I think that'll be a big difference in the fight and I think it'll be the key to victory."