LOS ANGELES (AFP) - Record-breaking US daredevil Nik Wallenda hopes to make history again this weekend by walking across the Grand Canyon on a tightrope, 1,500 feet (457 metres) above ground over the world-renowned landmark.
The 34-year-old, who was the first person to walk across the Niagara Falls last year, will be rigged up with multiple cameras and microphones broadcasting the death-defying feat live around the world.
And unlike the Niagara Falls walk, he will wear no safety harness for the stunt, likely to take him 25 minutes in searing temperatures over the famous tourist attraction.
"I'm confident in my ability. But the mental part is where I have to be very, very cautious. It's very challenging leading up to an event like this, it's a worldwide event... that really plays a role on me mentally," he told AFP.
Mr Wallenda, a seventh generation member of the Flying Wallendas circus family, said that as he steps out he will be thinking of his great grandfather Karl Wallenda, who died in 1978 after falling from a tightrope.
Video of the fatal fall in Puerto Rico is easily viewable online, and Mr Wallenda said it is a constant reminder of the risks - and that he must stop performing at a much younger age than his forefather, who died aged 73.
"He had said publicly that that's the way he wanted to go," the younger Wallenda said, but added: "I don't want to go that way... I wanna die in a bed next to my wife, at an old age over 100 years old. That's my dream.
"I don't want to die performing," he added.
In last year's Niagara Falls stunt, Mr Wallenda braved strong winds and heavy spray to walk on a cable suspended around 200 feet (60 metres) above North America's biggest waterfall, on the US-Canada border.
The Niagara walk earned him his seventh world record, after others including the highest and longest bike ride on a wire, which he performed live on NBC's "Today Show" in 2008.
On Sunday, he will step out into the void more than six times higher - a height greater than that of the Empire State Building - with nothing but a two-inch (five-centimetre) thick steel wire between him and the rocky canyon bottom far below.
Mr Wallenda has been planning the Grand Canyon walk for about four years, homing in on a remote location at the eastern end of the mighty geological chasm, on land operated by the Navajo Nation Parks and Recreation.
He began final training in Florida weeks ago, boosting stamina by walking repeatedly along a 1,000-foot long rope, and using wind machines to simulate gusts of up to 50 miles (80 kilometres) an hour.
Sunday's walk across 1,200 feet of rope could potentially be delayed in the unlikely event of winds of above 45 miles per hour, of if there was a risk of lightning. A new live broadcast attempt could then be made the following day.
There will be a seven- to 10-second delay on the live broadcast by the Discovery Channel - although Wallenda admitted that a slip or mishap would doubtless boost TV ratings.
He has trained for the worst, and said that - unlike his great grand-father who had an injured collarbone and double hernia, and grabbed vainly for the wire before falling to his death - he would be able to hold on if necessary.
"It's not like I just grab with my hands like people visualize. I wrap my legs round it, my hands round it, I hug that wire like a bear hug until help comes. I've got rescue teams that would be with me within a minute," he said.
That help would be in the form of rescue trolleys, which hang underneath the cable and could be rolled out in seconds on a winch system to Wallenda, clinging on for his life.
"The networks would love it if that were to happen because it makes incredible TV," he said, adding: "But I have no desire to end up that way, that's for sure."
The walk begins at 5pm on Sunday (8am Monday Singapore time) and will be broadcast live in 219 countries.