UPDATE: Aldo tweeted last night (Translation via MMA Mania):

"Let me be clear I'm not hurt again, I'm not hurt. I picked up a suspension (from) the Canadian commission and therefore should only return to training (after) 30 days this month. So once again, I'm not injured."

Aldo is apparently contending that the medical suspension he was under after UFC 129 prevented him from training enough to be ready for UFC 133.

Mendes' management told MMA Weekly that Mendes wants to go ahead and find an opponent for UFC 133 regardless of Aldo's plans.

UFC featherweight champion Jose Aldo has pulled out of his UFC 133 title fight against Chad Mendes according to Heavy.com.

Aldo, the final WEC featherweight champion, was named the UFC's first 145lb champ at a special ceremony at UFC 123 last November. He was initially expected to make his first title defense against Josh Grispi at UFC 125. Aldo suffered a neck injury and had to pull out of that fight.

Grispi lost badly to unheralded UFC debutante Dustin Poirier on the undercard of UFC 125.

Aldo finally defended his UFC title in a five round decision win over Mark Hominick at UFC 129. Aldo took a unanimous decision from the game Canadian, but Hominick ended the fight on a high note by taking Aldo down and ground and pounding the champ for much of the fifth round.

The cancellation of Aldo vs Mendes at UFC 133 is another in a long string of cancelled headliners including the lightweight championship fight between Frankie Edgar and Gray Maynard that was supposed to headline this weekend's UFC 130.

MMA Junkie spoke to Aldo's manager Ed Soares and got more info:

UFC president Dana White suggested that Aldo vs. Mendes could take place as early as UFC 133 on Aug. 6 in Philadelphia. But Soares said his client was hoping for more time before his next title defense. If Aldo is at full health when his suspension ends, he'd have a little less than 10 weeks to train for the matchup. But Soares said his client was hoping for a minimum of 12 full weeks to prepare. "Whether it's Chad Mendes or any other top contender, Jose is competing against the very best opponents in the world, and he wants ample time to prepare," Soares said. "When you're the champion, everyone is gunning for you, and it's important to be 100 percent." Heavy.com first reported the shuffle, but Soares insists his client didn't withdraw from the bout. While Soares said UFC officials had discussed a potential UFC 133 fight, he insists Aldo didn't turn down the matchup and was expecting to face the wrestling standout a little later this fall. However, Mendes has other plans. "Chad is looking to fight Aug. 6, for sure," Mendes' manager, Mike Roberts, told MMAjunkie.com. ""We're not going to wait for Jose Aldo. Chad wants to fight. If Aldo can't fight, Chad will move on and fight somebody else."

UFC 133 Fight Card so far, August 6 in Philadelphia, Pennsylvania.