Brazilian heavyweight Geronimo Dos Santos has fought in lesser known Brazilian mixed martial arts (MMA) promotions for some time. Months ago, news was broken that he was set to face off with Gabriel Gonzaga at UFC 153 in Brazil, marking his "big league" debut.

Now, it seems that fight is off, spelling trouble for Gonzaga, who is now left without an opponent little more than one week from the event at the HSBC Arena in Rio de Janeiro, Brazil, on Oct. 13, 2012.

Sherdog has the scoop:

Promotion officials announced Thursday that "Mondragon" has been forced to pull out of his planned UFC 153 scrap against fellow heavyweight Gabriel Gonzaga, though a reason for the Brazilian's withdrawal was not revealed. It is currently unknown if Gonzaga will remain on the bill.

Being that we're so close to the event, it seems unlikely that the UFC can find a suitable replacement for Gonzaga to fight. Heavyweight seems pretty booked up right now, and it would be a lot to ask for any fighter to step up on such short notice.

After a long list of main event switch ups thanks in large part to injuries, we will now be see Anderson Silva fight Stephan Bonnar in a light heavyweight non title fight in the UFC 153 main event.

For more news and updates on UFC 153 click here.