DeChambeau shot a second straight 66 and shared the lead with Lucas Herbert of Australia (63) at 12-under 132 at Emirates Golf Club.
One of the two players above him on the leaderboard is Bryson DeChambeau, the 25-year-old American seeking his first victory overseas. I'm swinging well, my body feels well.
"Whether it's air pressure, firmness values, miles per hour on the ball speed, spin rates...we're trying to figure out as much as possible so I can be as consistent as possible and obviously it's showing".
He continued: "Shoot, I'm still leading, obviously, it's fantastic".
Els played his first two rounds alongside two more stalwarts of the European Tour, Colin Montgomerie and Jose Maria Olazabal. I see scoring slowing down a little bit over the weekend in the afternoons.
DeChambeau joined Jack Nicklaus, Phil Mickelson, Tiger Woods and Ryan Moore in winning the NCAA and US Amateur titles in the same season in 2015, while his opening 64 in Abu Dhabi the following year had playing partner Chris Paisley labelling him as "quite possibly the most impressive player I have ever seen". I just felt uncomfortable, unfortunately, and consequently I am not ball-striking my best.
"I had a couple chances to right the ship and be three or four ahead, but I'm only one ahead".
DeChambeau, who has never won outside of America, carded successive bogeys at the seventh and eighth holes, only to strike back with consecutive birdies. "Just, you know, going on the memory bank, I guess", Els said.
Elsewhere, English duo Jordan Smith and Matthew Fitzpatrick are five shots off the lead on 11 under par, while Tommy Fleetwood, Lee Westwood and Andrew Johnson are one further back.