The world number five, who began the day's play at Emirates Golf Club as joint leader, rolled in two birdies in the final four holes to card a four-under-par 68.
Aside from three wins, Els has three seconds and three thirds among his previous 16 appearances in Dubai.
South Africa's four-time major victor Ernie Els rolled back the years to put himself in contention for a first victory since 2013 with a 65 to lie in second place alongside fellow former champion Alvaro Quiros on 11 under.
He continued: "Shoot, I'm still leading, obviously, it's fantastic". "But with my expectation levels, and how I know I can perform, I feel like I'm underperforming a little bit. I made it happen when necessary and hopefully I can have one more of those days and maybe even a better-ball striking day".
The rejuvenated Alvaro Quiros (71) of Spain looked like joining Li in second place, but wound up with a double bogey after hitting his second shot into the water on the 18th hole and was tied fifth at 12-under.
Els said he expects a mark of around 20-under-par will be needed to win the tournament, which was claimed by China's Li Haotong - who is just two shots off the lead - in 2018. But then, Bryson DeChambeau never has obeyed convention and when he tries to convert that advantage on Sunday into a first European Tour win, the American will set out to emphasise he is anything but a normal professional.
"I know even while not at my best, I can get it done", DeChambeau said.
"But again, going back to it being my first worldwide win, I really couldn't be more pleased to have this tournament be my first global win, European Tour win".
"But I'm still in the lead, still got the job done".
England's Matt Wallace fired a sensational eight-under par round to move into contention on 10-under alongside compatriot Callum Shinkwin, while Matt Fitzpatrick - who led after round one - finished two under on day two and sits on nine under.