Daniel Jacobs can no longer win the IBF middleweight title in his fight against Gennady Golovkin on Saturday after skipping a weight check on the morning of the bout.
Golovkin will defend his WBA super, WBC, IBO and IBF belts at Madison Square Garden.
The IBF title will still be on the line for the Kazakh fighter, but Jacobs will not be eligible to claim it even if he gets the better of his unbeaten opponent.
"Golovkin is defending his IBF title, however Jacobs cannot acquire the title with a victory because he did not participate in the required IBF same-day weigh-in," said IBF championships chairman Lindsey Tucker in a statement.
Speculation over Jacobs' reasoning for missing the weigh-in range from accusations of gamesmanship to claims the decision was taken to ease pressure on the American on the day of the fight.