Sauerland said yesterday: "It's the end of all dreams. The subject is closed. Axel is very disappointed."
Last week, Sauerland had said that the contract for the fight had been drawn up and was ready for signing.
But Showtime was concerned about lower than expected income from Tyson's last bout against Francois Botha and was now looking for a different opponent, possibly Donovan "Razor" Ruddock, Sauerland said, adding that he would now try to set up a fight between Schulz and the World Boxing Council champion, Lennox Lewis.
Russia's Anatoly Alexandrov retained his World Boxing Organisation super- featherweight title at the Palais des Sports in Paris on Monday night, stopping the Mexican Arnulfo Castillo in the eighth round.
Alexandrov was by far the more aggressive from the outset and the referee stopped the bout as he mercilessly laid into Castillo, who was reeling from a blow in the fifth round which gashed his left eyebrow.
Alexandrov, 31, who won the vacant title by beating France's Julien Lorcy in Paris last May, took his record to 35 wins and three defeats while the 27-year-old Castillo suffered his first defeat with his record now 27-1-2.
On the same bill, the veteran French fighter Jean-Baptiste Mendy retained his World Boxing Association lightweight championship, comfortably outpointing the Argentinian Alberto Sicurella. Mendy, 35, won on a unanimous decision.
The former world heavyweight champion Michael Moorer faces charges of drunken driving and evading arrest after driving his car into a ditch. Rutherford County police arrested Moorer, 31, of Boca Raton, Florida, early on Sunday morning after he crashed his Mercedes into a ditch.