The American carded a 24 under total as he won his first European Tour title 12 months ago but narrower fairways, thicker rough and firmer greens, coupled with mother nature sending a testing wind, means that score is highly unlikely to be matched this time around.
Only ten players were able to break par in the morning winds, and DeChambeau was enjoying having his game pushed to the limit in the desert.
"It's playing at least four shots harder a day if it was to stay like this, no doubt," he said.
"It's a very, very good test of golf and you have to make sure your wedge game is on and your iron play is on."
Padraig Harrington has seen it all in his many years on the European Tour and finished second at this event in 2001.
The Ryder Cup Captain was under par as he fired a 71 and he felt the greens were as big a factor as the narrow fairways.
"It is tough to hit the fairways but it's not playing long with the heat," he said.
"If you want to sort all the professional golfers out, just give us firm greens. Firm greens really sort us out and we find it difficult.
"If you do miss the fairways, coming into firm greens, it's very difficult."
Louis Oosthuizen is another Major Champion who carded a 71 and he felt he had his toughest day at Emirates Golf Club.
Played poorly today but a pleasure anyway to play a golf course in such a great shape, tough and fair! Well done @EuropeanTour, @OMEGAgolfdubai and @emiratesgc! This is how any @EuropeanTour event should be set up! 👏🏻👏🏻👏🏻— Edoardo Molinari (@DodoMolinari) January 23, 2020
"This is by far the toughest I've ever seen it," he said. "The fairways are tight. The rough is close to U.S. Open standards and the greens are rock hard and really crispy."
Multiple European Tour winners Joost Luiten and Edoardo Molinari could not finish the day in red numbers but were both full of praise for the layout, with Luiten saying: "It's a great set-up, I like it."
And Molinari tweeted: "Played poorly today but a pleasure anyway to play a golf course in such a great shape, tough and fair! Well done @EuropeanTour, @OMEGAgolfdubai and @emiratesgc! This is how any @EuropeanTour event should be set up!"