Gennady Golovkin says his bout with Saul 'Canelo' Alvarez in Las Vegas on Saturday is the "biggest of this era".
Golovkin holds the WBA, WBC and IBF middleweight titles, although if Alvarez wins he will not take the WBC belt, so that would become vacant.
Golovkin, 35, is looking to extend his undefeated professional record to 38 fights against Mexican Canelo, 27.
"It's the biggest day for boxing, for this era - this huge history fight," said Kazakh fighter Golovkin.
Alvarez is a three-time world champion in two classes, and his only defeat in 51 fights came against Floyd Mayweather in 2013.
His promoter, Oscar de la Hoya, says the bout at the T-Mobile Arena, where Mayweather beat UFC's Conor McGregor three weeks ago, will be "hell".
"I don't like to talk a lot. I'm prepared," said Alvarez.
"I know what it's going to be: a tough fight. That's what I'm ready for. I want you to all enjoy it like I'm going to enjoy it."
'McGregor v Mayweather was not of interest to me'
Mayweather won his 50th consecutive professional fight with a 10th-round stoppage of UFC star Conor McGregor in August, in one of the most lucrative fights in boxing history.
"Right now is a true boxing fight," Golovkin told BBC Sport. "I did not watch fight between Mayweather and McGregor because it is not of serious interest to me.
"If this fight was a charity fight, of course I would have watched, but because it was a business fight or a funny project it is not interesting to me.
"This is a totally different situation."
Golovkin missed the birth of his daughter while preparing for the Alvarez fight.
He said: "My wife feels good and my baby is good. She understands my situation and that this is business.
"The last three months I have just stayed in the gym and right now I just 100% want to win and I give everything for this fight.
"I feel different, more true, right now my focus is 100% on boxing. I am very ready and very excited."
Alvarez dismissed suggestions that the fight will be "overshadowed" by the Mayweather-McGregor bout.
"That is a mistake for people to say that," he said. "This is a fight that people have been wanting and waiting to see.
"Every fight I have is important at its moment. This is another one of those fights and it will mark another chapter in my history."
Analysis: 'Fight of the decade - Canelo wins'
BBC Radio 5 live boxing analyst Steve Bunce
I wrote at the time this was confirmed - this is a fight of the decade. There are very few fights you consider for that title.
I was never with Golovkin. One of the reasons why I have stuck with Alvarez is because I saw the job he did on Cesar Chavez Jr in May. He nullified a big guy.
There was a big question mark over Golovkin against Daniel Jacobs last time. There were moments in that fight where he looked to be struggling.
Their last two fights have made me resolutely believe it is a Canelo victory.
A carnival atmosphere - Canelo fans out in force
Ade Adedoyin, BBC World Service reporter in Las Vegas
There hasn't been quite the same level of hype and hysteria that we witnessed ahead of the Mayweather-McGregor fight three weeks ago but there does appear to be an appreciation of the magnitude of this match-up from both sets of supporters.
Many are suggesting that it's not just the belts on the line but also that unofficial title of best pound-for-pound fighter in the world.
Vegas is gearing up for Mexico's Independence Day celebrations and that has added to the occasion. There will be a concert on Friday night featuring a popular Mexican band called Mana. A lot of people have flown in for that and the fight the following night.
So it is no surprise that the Alvarez supporters outnumber the Golovkin fans. Regular chants of "Ca-ne-lo" and the sounds of a mariachi band helped to create a carnival atmosphere in the lobby of the MGM where the grand arrival ceremony took place on Tuesday.
As for Golovkin, he is leaving nothing to chance. A select number of media were given the opportunity to interview him before the press conference and we were advised he would rather not shake anybody's hand as a precaution as he is concerned about picking up an injury or illness before such a big occasion.