UFC lightweight champion Anthony Pettis hasn't fought in over a year, yet he continues to get called out by fighters in his division. This time, it's Nate Diaz who has the champ's attention.

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Pettis and Diaz spent time together while filming the upcoming season of "The Ultimate Fighter 20." Diaz was an assistant coach for the team led by Gilbert Melendez, who will challenge Pettis for the lightweight title in December. After filming was done Melendez said in an interview with MMA Junkie that Diaz had more tension with Pettis than he did.

"He's such a cholo, bro," Melendez said of Diaz. "He don't smile one bit; he don't say hi to nobody. I like having him around; he has a great intimidation factor. He's all business. He's always ready to go. Most people just give him his space. They don't want to call his bluff. (He would say about fighting Pettis), 'Whenever you want, Gil, you let me know.' I'm like, 'Nah, Nate, it's cool.'"

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But Pettis is unamused.

"I definitely want to kick his ass," Pettis said about Diaz during a fan Q&A session. "Anybody in my weight class, I want to kick that ass. But man, he had his chance. I was on the show with him for seven weeks. I seen him everyday, and he didn't say anything. So once the show is over, he wants to talk afterward? It doesn't matter."

Pettis has had to field barbs from former champion Benson Henderson and up-and-coming contender Khabib Nurmagomedov, among others. They criticize the champion for his constant injuries and lack of activity since winning the title. "Showtime" suffered a knee injury when he won the belt last August, and then filming the show delayed his return even more.

As for Diaz, Pettis doesn't pay him any mind as he has a slew of other contenders in the 155-pound division to deal with.

"He had seven weeks to say something," Pettis said. "He didn't say anything, so that's what it is."