UFC featherweight champion Jose Aldo (18-1) was set to fight Josh Grispi in the co-main event of UFC 125: Resolution this New Years Day, but is now forced to the sideline with a training injury.

Aldo suffered from a compacted vertebrae, causing tingling in both arms. He will be out for at least a month, if not longer.

Aldo is considered one of the top three pound-for-pound fighters in the world. He holds a record of 18-1 and has not lost a fight since 2005. He has one all eight of his WEC matches, with notable victories over Cub Swanson, Mike Brown, Urijah Faber and Manny Gamburyan.

Grispi holds a record of 14-1 and is riding a 10-fight winning streak, having finished nine out of those 10 fights in the very first round. He has won all four fights for the WEC, including submission victories over Mark Hominick, Jens Pulver, and L.C. Davis, and a TKO victory versus Micah Miller.

UFC 125 will feature a lightweight championship bout. Frankie Edgar and Gray Maynard will be throwing down, so put your MMA gloves on. Clay Guida, Chris Leben and Nate Diaz are also scheduled to fight. It's still too soon to tell if a replacement fighter will be recruited to face Grispi or if the fight will simply be postponed, but we'll keep you posted.