Vienna - Kenya's Olympic and world champion Eliud Kipchoge said on Thursday he was confident of busting the mythical two-hour barrier for the marathon this weekend, an achievement he ranks with man's first landing on the moon.

The 34-year-old will make the attempt on Saturday in Vienna in a huge park where the path has been specially prepared to make it as even as possible. Two years ago he tried, and failed narrowly, at Monza, Italy

Kipchoge already holds the men's world record for the distance with a time of 2:01.39, which he set in the flat Berlin marathon on September 16, 2018.

But now, on a surface partly retarred and prepared with other features such as a banked corner that can save time and avoid injury, he is aiming to set a new mark. He will be aided by pacemakers, who are taking turns to support him.

Because of way the run is being set up and paced the International Association of Athletics Federations will not validate the time as a world record.

"Vienna is (about) running and making history in this world, like the first man to go to the moon," Kipchoge told reporters on Thursday at a press conference in the Austrian capital, adding he wanted to show that "no human is limited".

"The course is extremely good. I'm happy with the course," he said, adding he was trying to "stay as calm as possible" for Saturday.

The 42.195km stretch has been prepared so that it should take him just about 4.5 seconds more than a computer-simulated completely flat and straight course, according to an analysis by sports experts at Vienna University.

In total, he will only have to descend 26 metres in altitude down and climb 12 metres, the experts said.

Kipchoge attempted the feat in May 2017 on the Monza National Autodrome racing circuit in Italy, finishing in a time of 2:00.25.

He says he is mentally stronger now and he is "confident" that he can get it "the second time".

"My training has been the same, my coach has been the same, my management, everything has been the same. Now the thinking is different," he said.

"I feel more prepared. I feel more ready."

Kipchoge will begin his run between 05:00 and 09:00 (SA time) - the exact time will only be set on Friday - amid favourable weather conditions: very low wind speed, temperatures of 5 to 9 degrees Celsius, and no rain, according to organisers.

The founder of the main sponsors, Ineos, British billionaire Jim Ratcliffe, is taking a personal interest in the challenge because he himself competes in Ironman triathlons.

The world marathon record has, for the past 16 years, been contested uniquely between athletes from Kenya and Ethiopia. The two nations are also fierce rivals for distance medals on the track.

Kipchoge's record was almost beaten last month in the Berlin marathon by Ethiopia's Kenenisa Bekele, who ran 2:01.41, just two seconds short of the world mark.