'NCIS' Regular Wilmer Valderrama Bragging About Popularity Saving the Show, 'Competitive' With Costar Sean Murray Behind the Scenes

NCIS fans are already feening for season 21 and it won't be long until Wilmer Valderrama returns as tough-as-nails Special Agent Nick Torres in the crime drama series.

RadarOnline.com has exclusively learned about some behind-the-scenes tension stirring up due to Valderamma taking credit for the show's renewal, a TV insider spilled.

The '70s Show heartthrob has seen beefed-up storylines in the wake of Mark Harmon's departure, including a nail-biting cliffhanger after his character went undercover in jail to seek answers about a supposed Russian terrorist attack.

It's claimed the boastful screen stud and costar Sean Murray, who portrays Special Agent Timothy McGee, have a discreet rivalry.

"They may be playing buddy-buddy in the show promos, but they have to do that," said an insider. When the cameras aren't rolling, "they're still as competitive as they ever were — maybe more so now that Wilmer's got it in his head that fans love him more!"

The tipster said Wilderamma knows what he brings to the show and is eager to get his money's worth. "He's throwing his weight around even more — and demanding perks for next season." It was pointed out that "Sean's popular, too, and he gets top billing."

Meanwhile, another source disputed the claims about Valderrama, casting doubt on the costar rivalry rumors and that he believes to be greatly responsible for the show's success.

RadarOnline.com has reached out to a rep for Valderrama for comment.

Fans previously learned that another season was around the corner in February. At the time, an action-packed clip was shared, teasing more jaw-dropping moments to come.

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"BIG news – get ready to grab your gear, we've got more work to do. #NCIS has officially been renewed for Season 21! We'll see you there," it read.

Theories have already been running wild after last season's twist involving Torres. "I'm guessing an ex-boyfriend of their mom that likely stole mom's life savings and ran," one Reddit user posted. "I'm assuming he's still running the same sort of sting with the kid's mom too. But for Nick to want to kill him, he had to have done something more serious than that."