Caleb Truax says James DeGale is underestimating him again before Saturday's IBF world super-middleweight title rematch in Las Vegas.
The American, 34, took the title from Briton DeGale, 32, with a shock points win in London in December.
Truax said: "I think DeGale overlooked me last time and I think he's doing it again this time.
"I see him talking about fighting David Benavidez and George Groves. Did he not learn his lesson the first time?"
DeGale, who was rated at odds as short as 1-100 with some bookmakers for that bout, blamed his defeat by Truax on rushing back from "reconstructive surgery" on his shoulder but his rival has said that he is using that as "an excuse".
It was only DeGale's second professional defeat, following the majority decision against George Groves for the British title in London in 2011.
"Caleb Truax is not on my level. I'm miles above him," said DeGale. "On 7 April, I'm going to show everyone why and show everyone what I'm all about.
"As soon as the doctor said that some athletes come back after six months from my injury, I was determined to fight in 2017.
"Everyone can see that I was slow in the ring. I was ashamed of my performance. It was embarrassing and I'm looking to erase that on 7 April.
"For the past six weeks, I've felt so much better. My jab is sharp again and everyone will see that when I become a two-time world champion."