Mikkel Kessler told Ringside that Carl Froch has improved as a fighter since they first met in Denmark in 2010.
Kessler, the current WBA super-middleweight champion, edged a thrilling bout in his homeland three years ago, beating the Nottingham puncher on points, despite picking up a nasty-looking wound above his eye during the contest.
The 34-year-old will face IBF titlist Froch once more in a unification bout at London's 02 Arena on Saturday, May 25 - a clash you will be able to see live and exclusive on Sky Box Office HD.
And he reckons the English boxer's power and long limbs will make him a tough man to conquer in the pair's highly-anticipated rematch.
"You have to have a game-plan against Carl, who has longer arms than I thought and is physically strong, as if you hit him he will hit you right back," said Kessler, who defeated Brian Magee in December to seize his strap.
"I know some more things about him now having seen his previous fights against guys like Lucian Bute, but I think Froch, who is not as fast as Joe Calzaghe but hits harder, has got better (since we fought).
"I always expected him to beat Bute and I know I will be the underdog when we fight in May, but I like being the underdog!"
Kessler went into his initial bout with the Cobra on the back of a loss to Andre Ward - who Froch also succumbed to in December of 2011 - and admits that if he had been beaten by the Brit, his in-ring tenure would have come to an end.
But the Copenhagen-born star says his hard graft paid off in Herning and reckons that his performance against Northern Irish fighter Magee late in 2012 proves he still has a lot to offer between the ropes.
"I had a lot of boxing experts in Denmark and from around the world who said I was finished before I fought Froch and I started to doubt myself a little bit," added Kessler, whose only other professional reverse came at the hands of Calzaghe six years ago.
"I knew I had to have a new trainer (Jimmy Montoya) and work hard and go in with all my heart, as I knew that if I lost it was the end of my career but I won.
"And I showed against Magee, who is a good fighter, that I have stayed focussed on my boxing, that I am still here and I am still a world champion."