Haye is Britain's first heavyweight world champion since Lennox Lewis
World heavyweight champion David Haye says he will not underestimate American John Ruiz when he defends his WBA title for the first time on 3 April.
Haye, 29, who will face the 38-year-old two-time former champion in Manchester, admitted he will have to be wary of his opponent's uncompromising style.
"He's a lot tougher and a lot more durable than a lot of people give him credit for," said Londoner Haye.
"He's awkward, he rushes his punches and comes in heavy with his head."
Haye claimed the heavyweight title by beating giant Russian Nikolay Valuev in November.
The Briton is likely to face an entirely different test against Ruiz, whose trainer Miguel Diaz has spoken about the need for his fighter to attack Haye early.
"He's an ugly type of fighter that drags people down," Haye added.
"I can't allow him to upset my rhythm. I've got to go out there in the first round and apply my skill set and do what I do best.
"I don't think he can live with me when it comes down to really holding your feet and throwing bombs.
"I think I punch harder and faster than him and I think I'll be landing before he lands."
Ruiz has been beaten eight times in a 54-fight career, with one draw and 30 knockouts and last fought in November, beating Adnan Serin inside seven rounds.