Gennady Golovkin feels Kell Brook will provide him with his biggest test despite the welterweight's huge step up in weight division for their September 10 bout.
Brook (36-0-KO25) is moving up to middleweight for the first time in his career to take on Golovkin in a battle of two unbeaten fighters at the O2 in London, an event which will be broadcast on Sky Sports Box Office.
But the Kazakh, who has won 32 of his 35 bouts by knockout, says he was surprised by Brook's size at Thursday's news conference in New York and he is not going to be taking anything for granted.
Golovkin will be fighting in England for the first time in his career when he puts the WBC, IBF and WBA Super titles on the line against the man from Sheffield.
"I know it will be an amazing atmosphere with huge fans – true fans – and it is the biggest test for us," Golovkin told Sky Sports.
"I am very excited. I know London fans are huge fans, and that I respect. They understand boxing and I want to bring the UK fans a big, dramatic show.
"Just seeing him for the first time now, it was very interesting for me. I respect Kell – he is a man and he is a true fighter."
Brook's step up has been branded a 'joke' by Chris Eubank Jr, whose team were unable to reach agreement over a fight with Golovkin, and the Kazakh says past history of fighters going up in weight makes him concentrate even more.
He said: "I know history like Sugar Ray Robinson, Sugar Ray Leonard, Roberto Duran. Manny Pacquiao, he came up to junior middleweight and beat Oscar De La Hoya, Miguel Cotto, Antonio Margarito.
"This is the biggest test for me. He is the same height as me and he's a big guy. I saw a couple of his fights and he is a strong guy, the best fighter in his division."
Trainer Abel Sanchez will again be plotting a way to beat Brook after failing to do so with another of his fighters – Carson Jones – in 2012 and 2013.
And he is also playing down any advantages Golovkin might have in being a true middleweight.
Sanchez said: "They already beat me once and they aren't going to beat me twice. They are great coaches. We came close with Carson but that was a very green and raw Kell Brook we fought.
"I believe they have transformed him into a great fighter – the best welterweight in the world. We're looking forward to the atmosphere and the challenge he will bring.
"If you go back and look at the guys who stepped up, the problem for the bigger guy was that they were faster with hands and feet, and they had the right game plan. If they have the right plan he could present a big problem for us."