AUBURN HILLS, Mich. -- This has been a difficult year for Antonio Rodrigo Nogueira.
He was knocked out in the first round by Cain Velasquez on Feb. 21, and a September rematch with Frank Mir had to be postponed when Nogueira suffered a knee injury.
But this rough period hasn't dampened the former UFC interim and Pride heavyweight champion's spirits. He remains as upbeat as ever.
"He's good," Nogueira's manager Ed Soares told ESPN.com. "He's a great guy, so he's always in good spirits. It's pretty hard to get that guy bummed out.
"The knee: He is rehabbing it right now in Brazil. He's not training, just rehabbing the knee."
There is no definitive time for Nogueira (32-6-1) to resume his UFC career, but he's a veteran and won't step into the Octagon until his body is fully healed.
"I'd like to see him come back when he feels 100 percent," Soares said. "I am assuming it will be sometime in late spring, early summer."
When the 34-year-old Nogueira returns, there is one fighter he wouldn't mind seeing in the opposite corner -- Mir. He isn't calling Mir out, that's not Nogueira's style, but he would relish a chance to even the score.
Mir took Nogueira's interim title with a second-round stoppage at UFC 92 in December 2008.
"I think [Nogueira-Mir II] is a great fight," Soares said. "Does he want to even the score? Absolutely! Is it a motivating factor? Definitely!
"Big Nog is a warrior. He's never chosen an opponent. Whoever you put in front of him, he will fight."
Soares is in Auburn Hills to oversee Lyoto Machida, who faces Quinton "Rampage" Jackson on Saturday at UFC 123. Both Machida and Jackson are former light heavyweight champions looking to get back in the win column.
Franklin McNeil covers MMA and boxing for ESPN.com. He also appears regularly on "MMA Live," which airs on ESPN2. Follow him on Twitter at www.twitter.com/Franklin_McNeil.