Woody Harrelson and Matthew McConaughey may be brothers. Justin Theroux wants in

Justin Theroux wants to be part on the tight-knit relationship Woody Harrelson has with Matthew McConaughey.

Theroux, who stars alongside Harrelson in the upcoming HBO series “White House Plumbers,” says they got along famously, but he knows he’s got his work cut out for him if they plan to take it to the next level.

“We did have a bit of a bromance,” Theroux told “Entertainment Tonight.” “I mean, I’m in competition with McConaughey, who is, I guess, is the OG bromance, but I’m trying to peel them away and see if we can have an open bromance.”

There’s been a lot of chatter recently that McConaughey, 53, and Harrelson, 61, are actually brothers. Theroux is onboard with that.

“I think it would be great,” he said. “I’m sure they could both go spit in a cup somewhere and solve this pretty quickly. I’m going to put my spit in a cup and just take my chances. Who knows?”

Theroux also says the pair sound like they are one and the same.

“I can’t tell whether it’s just their sort of slow Southern and Texas drawls or I think Texas figures in there somewhere,” he said. “It’s just a mentality. They’re both so wonderfully sort of blissfully relaxed all the time.”

Harrelson and McConaughey, who co-starred in “True Detective,” have hinted in separate interviews that they may have the same father.

During an appearance on “The Late Show with Stephen Colbert” earlier this week, Harrelson noted there “is some veracity” to that possibility, saying that McConaughey’s mother, Kay, teased the idea during a group outing in Greece.

“I mentioned something about regrets and I said it’s odd that my father has no regrets,” Harrelson said. “I’ve known (McConaughey’s mother) a long time and she goes, ‘I knew ... your father.’”

“It was the ellipses I found a little troubling, or interesting,” Harrelson added.

Harrelson also told Colbert that about nine months before McConaughey was born, his mother was “on a sabbatical from her relationship with his supposed father, Jim.”

McConaughey detailed the same story when he was a guest on the “Let’s Talk Off Camera with Kelly Ripa” podcast recently.

“Everyone was aware of the ellipses that my mom left after ‘knew,’” he said. “It was a loaded K-N-E-W.”

Interestingly, Harrelson and McConaughey are working on starring in a new Apple TV+ comedy series, “Brother From Another Mother.”

Harrelson’s father was a convicted killer who died in prison in 2007.

McConaughey suggested taking a DNA test to find out the truth made him hesitant because it would trouble him to learn the father he grew up with wasn't his real dad.

“It’s a little easier for Wood to say, ‘Come on. Let’s do it!’ because what’s the skin in it for him?” he told Ripa. “It’s a little harder for me because he’s asking me to take the chance ... I got a little more skin in the game.”

This article was originally published on TODAY.com