Walt Disney Television/Jeff Neira(NEW YORK) -- In 2012, high-wire artist Nik Wallenda walked across Niagara Falls. In 2013, he walked across the Grand Canyon.  But Sunday night, he'll face the scariest challenge of all: walking across New York City.

More specifically, Nik will be walking on a 1,300-foot-long cable suspended 25 stories above street level across New York's legendary Time Square. He'll be joined by his sister, Lijana, in her first performance since she fell 30 feet off a tightrope in 2017.

"She'll come out to the middle [of the wire], she'll sit down, we'll meet there," Nik told ABC News. "I'll then step over her and then she'll get back up and she'll walk to one side, I'll walk to the other."

Why Times Square?  Nik told ABC News, "Because it's Times Square! No one in the world's ever walked a wire over Times Square...and to be honest, the distractions of Times Square were a fascination to me."

"The key to wire walking is not getting distracted," he said at a press conference on the top of 1 Times Square, the location of the New Year's Eve ball drop.  "Every distraction you can imagine is right down there. So to me, it was about pushing myself to be better at what I do."

"There are a lot of distractions...the stability of the wire, the fact that my sister's at the other end coming towards me....there's definitely a lot going on," he added. "More than I've ever had to deal with in my entire career."

Also distracting? The wire he's walking on is thin. Really thin.

"It's a little smaller than my thumb...very close to the size of a quarter," Nik says.  

Highwire Live in Times Square with Nik Wallenda airs live Sunday at 8 p.m. ET on ABC.

Copyright © 2019, ABC Radio. All rights reserved.