HOUSTON -- At a recent fan Q&A inside Toyota Center, Anthony Pettis seemed to speculate on whether his last opponent, UFC lightweight champion Rafael dos Anjos, is completely natural.

Pettis, the former lightweight champion, was asked to give his opinion on a Dec. 19 title fight between dos Anjos (24-7) and Donald Cerrone (28-6). In a subtle way, Pettis suggested the result of the fight might be influenced by the UFC's anti-doping policy through USADA, which went into effect this year.

"If the right [Cerrone] shows up and the testing is good, I think [Cerrone] could be champ," Pettis said.

ESPN.com asked Pettis, who lost the UFC title by decision to dos Anjos in March, to elaborate on the comment immediately after.

"I'm never going to be that guy who goes out and says I lost because he's on this or that, but you look at the fight and you look at how he physically looks, it speaks for itself," Pettis said. "I'm not trying to go out and say this guy is cheating, but we'll find out now that we have real testing. We'll see if this guy makes 155 and how he looks."

Pettis isn't alone in questioning dos Anjos' physique. In July, before the fight was announced, Cerrone posted side-by-side photos of dos Anjos online, showing how he has changed physically over time.

When a fan asked Cerrone when the fight was going to happen, the No. 1 contender responded, "Whenever he cycles off and can pass a blood test."

Dos Anjos, 30, shrugged off Cerrone's comments. In an interview with MMAFighting.com, he said the photos were taken so far apart and at different points in his training, it was to be expected he'd look different. He has never failed a drug test in his career.

The Brazilian champion was urine-tested by the Texas Department of Licensing and Regulation on the night he beat Pettis. The new USADA program, which dos Anjos has not been tested by yet, incorporates blood testing.

"He passed the test in Texas, so right now he's innocent," Pettis said. "But hopefully we'll find out again, especially in his next fight. The new guy [UFC vice president of athlete health and performance Jeff Novitzky] is on it. He's looking at where the rumors are."

Pettis is willing to answer questions about dos Anjos if they're asked, but he says that's not his focus. He's scheduled to fight former Bellator MMA champion Eddie Alvarez on Jan. 17 in Boston and believes a win there would set him up for a shot to reclaim his title.

Prior to losing the belt, Pettis was talking about "legacy fights," and he says that's still his interest. He wants his belt back, for sure, but potential matchups against Cerrone, Khabib Nurmagomedov and even dos Anjos aren't what he considers "legacy fights."

He'll be paying close attention to a featherweight unification bout between Jose Aldo and Conor McGregor at UFC 194 on Dec. 12. Pettis admits he'd like to fight the winner in 2016.

"I was the champ. I've proven before that I'm the best at 155 [lightweight]," Pettis said. "I have a small window where I feel like I'm about to hit my prime. I still want those big fights. Honestly, the guys at 155 -- I want to fight [dos Anjos] again, but [Cerrone]? I already beat him. The Russian [Nurmagomedov] is working his way up, but he's not exciting.

"Fighting Aldo or McGregor is exciting. Fans will pay to see that."

Ahead of his fight on Jan. 17, Pettis says he'll be doing something different in that he has built a training camp entirely focused on him. He's still at his longtime training home at Roufusport in Milwaukee, but he doesn't attend pro practices anymore and will do part of his work at a new facility that he and his brother, UFC flyweight Sergio Pettis, have opened. Wrestling coach Israel "Izzy" Martinez, a longtime member of Jackson-Winkeljohn MMA, will also be involved, according to Pettis' striking coach, Duke Roufus.

Pettis' camps will fall more in line with what professional boxers have done for years -- something that UFC president Dana White has encouraged, as he believes it will lessen injury.

"I stopped training with the team," Pettis said. "It's not anything personal against those guys, but I'm doing my own thing. I'm building a camp and bringing in select people to spar. I hire them and make sure they're there for me.

"I'm looking at [Bellator lightweight] Michael Chandler as a training partner. He has fought Alvarez a bunch of times, so I think he brings a good amount to this camp. It's expensive, but it's worth it. If I have to drop $7,000 into one sparring partner, but it saves me from losing seven months of my career due to injury where I'm possibly making hundreds of thousands, it's worth it."