Borg was suffering from a viral illness and has been forced to withdraw from the flyweight title fight, the UFC said in a statement, adding he "was deemed unfit to compete by the UFC medical team."
Borg released a statement on Friday to MMAWeekly.com, saying, "First, I want to say I'm sorry to the fans and to Demetrious Johnson for being unable to fight. I want to say thank you to Dr. Davidson, the UFC and to Jeff Novitsky for looking out for my health and best interests."
A female bantamweight title fight between Amanda Nunes and Valentina Shevchenko will now headline UFC 215, which takes place at Rogers Place. Ironically, that title bout was waved off the day of the fight at UFC 213 in July, when Nunes fell ill.
According to sources, the UFC is looking to potentially rebook the Johnson-Borg flyweight championship at UFC 216 on Oct. 7 in Las Vegas. The UFC has not yet announced Borg's removal from UFC 215.
Johnson (26-2-1) was seeking his 11th consecutive title defense, which would have surpassed former middleweight champion Anderson Silva's mark of 10. The 24-year-old Borg (11-2) was set to compete in his first UFC title fight.