The upcoming main event of UFC 215 in Edmonton on Saturday between flyweight champion Demetrious Johnson and Ray Borg has been called off.

Borg has been forced to withdraw from the fight due to a "viral illness," the UFC announced Friday.

"Due to a viral illness to UFC flyweight contender Ray Borg, the main event bout against champion Demetrious Johnson at UFC 215 has been cancelled. Borg was deemed unfit to compete by the UFC medical team," a statement from the UFC said.

The Women's bantamweight title fight between Amanda Nunes and Valentina Shevchenko will be moved to the main event. The UFC said customers could request a full refund on tickets purchased at point of sale.

The flyweight fight between Henry Cejudo and Wilson Reis was moved to the Pay-Per-View card and the lightweight bout between Mitch Clarke and Alex White will now air on the televised prelims.

With a win at UFC 215, Johnson was set to break Anderson Silva's UFC title defence record with his 11th win.