"Nikolai is already preparing for this fight. He is leaving for Okinawa [Japan], where he will be practicing for about a month. He will then return, and later continue practicing in Germany," Boris Dimitrov said.

Valuev, dubbed the Russian Giant, lost his title bout to Ruslan "White Tyson" Chagaev in April of 2007, suffering his only defeat to date. They later scheduled a rematch, first for May and then for July of 2008, but the match was put off due to Chagaev’s injury, and he was declared champion in recess.

Valuev reclaimed his WBA belt in August 2008 after defeating two-time WBA heavyweight champion John Ruiz, and then retained his title by beating four-time champion Evander Holyfield of the United States last December.

Thirty-year-old Chagaev (25-0, 17KOs) returned to professional boxing last month to face Carl Davis Drumond (26-1, 20 KOs) in Mecklenburg, Germany. He defeated the previously unbeaten Puerto-Rican in a six round technical decision.

Following the fight with Drumond, the WBA ruled that Chagaev’s next fight must be against Valuev, but permitted the Russian to hold another bout before facing the champion in recess from Uzbekistan.

The WBA extended on Tuesday the deadline for the fight between Valuev and Chagaev from July to September, prompting criticism from Chagaev’s promoter Klaus-Peter Kohl, who wanted an earlier date.

Dimitrov said Valuev was offered a choice of having a bout with four heavyweighters, including Holyfield and John Ruiz, but he declined.

"As soon as the WBA announced its decision [on the deadline], we said that we are not holding a fight with anyone other than Chagaev," Dimitrov said.

"Kohl said that the initial date of 26 July suits him. We told him that this date suits us as well," Dimitrov said.