Leading up to Friday’s Nets vs. Knicks face-off, two of the competing athletes are having a real catfight.

The Knicks’ new 7-foot center, Robin Lopez, has harsh words about his twin brother, Brook, who plays for the crosstown competition.

More specifically, he’s trash-talking his sibling’s pet.

“Brook’s cat is very two-faced,” Robin tells The Post. “Everybody loves Brook’s cat. To everybody’s face, he’s such a nice cat. And it may sound like I’m joking, but I am dead serious. He acts like a lazy, sweet cat when everybody is looking. But when their heads turn, he’ll try to chase after [my cat] Edward. The second I lay eyes on him, he’ll act like, ‘I’m a cherub. I’m innocent.’ I’m not buying it.”

In fact, the brothers don’t live together because of their felines: Brook’s kitty Poupin — French for “chubby” — and Robin’s majestically monikered Prince Edward Zephyr. (Each cat has his own Instagram account, naturally.)

When the Knicks signed Robin to a four-year deal worth $54 million in July, Brook thought about opening up his West New York, NJ, townhouse. “It might be permissible for him to live in my residence,” Brook told the YES Network at the time. “I am thinking sublet — maybe the basement, or a little cupboard under the stairs a la Harry Potter.”

But the 27-year-olds, who are identical save for Robin’s Sideshow Bob hairdo, ultimately decided against rooming together. (Robin landed in Westchester, near the Knicks’ practice facility.)

“We thought about it,” Brook tells The Post. “But the cats really wouldn’t get along. They just wouldn’t allow it.”

A Nets player and a Knick as roomies? Sounds like a sitcom. While the brothers have faced off on the hardwood before — most recently, when Robin was with the Portland Trail Blazers — Friday’s game at Madison Square Garden is their first match-up as New York hoops stars.

Brook says there’s no question the Nets will come away with the win, while Robin predictably has another take.

“I am going to get to dunk on [Brook], and I will block him at least twice,” Robin says matter-of-factly. “I’m generally going to destroy his soul.”

Born in Southern California to Deborah Ledford and now-estranged father Heriberto Lopez, a Cuban baseball player, the twins are the youngest of four boys. They were raised in Fresno by their mom, who was an elite swimmer, and began playing hoops as kids — looking up to their older brother Alex, who played at the University of Washington.

Robin and Brook were recruited by Stanford (where Robin reportedly dated golfer Michelle Wie) and, during their sophomore seasons, their squad reached the Sweet Sixteen. The siblings opted to leave school early for the NBA, and both were first-round draft picks in 2008. The Nets selected Brook, while Robin was scooped up by the Phoenix Suns (he later played for the New Orleans Hornets as well as the Trail Blazers).

Unlike other ballers, these two aren’t chasing VIP tables at Avenue or flaunting flashy wardrobes — though Robin did don the costume of Doc Brown from “Back to the Future” at New York Comic Con in October.

The brothers unabashedly love comic books and, according to a NY Times profile, would frequently squeeze their extra-tall frames into a college pal’s compact SUV to hitch rides to the comic-book store. While at Stanford, they once famously ditched practice for a day of fun at Disneyland. As children, their interest in comic books was nurtured by their grandmother, who provided the boys with endless art supplies and a room in her home to draw and paint.

Now Brook and Robin are collaborating on a number of projects, including a video game and superhero television pilots. The pair agree that living in the same area again has been great for their relationship. The avid baseball fans were able to attend the World Series at Citi Field together, and they regularly meet for dinner. (As for double dates, Robin says he’s “not single,” while Brook has no comment on his relationship status.)

“[Robin and I] got to hang out a week ago, so we just ordered Outback [Steakhouse]. It was all four brothers. We were able to sit in my room and watch TV and chill,” says Brook, who this summer signed a $60 million deal to continue his now seven-year tenure with the Nets. He insists that even though he and Robin are identical twins, they have their differences.

“Robin is the exaggerated version of me. He’s more of a cartoon character. He’s known for his mascot beatings, too,” says Brook of his brother’s notable WWE-esque feuds with NBA mascots. Robin’s spree started in 2013 when he jokingly brawled with Detroit’s equine mascot Hooper after the horse donned a look-alike wig and, since then, he’s been involved in numerous other playful attacks, leading to demonstrations faux-protesting his “violence.”

Robin admits he’s still wide-eyed over being in the Big Apple spotlight.

“I was doing layup lines at the Garden at halftime and I look toward center court. There’s Tracy Morgan, and he gives me a little fist pump,” he says. “That made my day. It’s a lot of fun to be recognized in New York.”

Their mom, who is in town for Thanksgiving, will be here for the big game, too.

“She tries to stay neutral,” says Robin. “Whatever team’s arena she’s in, she tries to wear that jersey. And she will wear the other team’s hat.”

Come tipoff, the pair has no trouble putting aside their goofy chatter. In fact, they don’t speak at all.

“It’s just the way it is. We’re out there for business,” insists Brook, who isn’t feeling the heat of being the visiting team.

“Is it at MSG? We’ll have Robin worry about all of the tickets for my family,” he says.

Regardless of the outcome, it’s New York basketball fans who will win with these colorful giants on the court.

“I think Brook has the advantage in a sense because he knows the city and knows what to expect,” Robin says. “But I don’t think he’s ready for my energy and how pumped I am going to be on the floor.”