World number 527 Ernie Els put himself in contention for a first win since 2013 with a seven-under-par round of 65 at the Dubai Desert Classic.
The four-time major winner carded seven birdies and an eagle to reach 11 under, a shot off the lead after 36 holes.
"I'm swinging well, my body feels well. Just, you know, going on the memory bank, I guess," said Els, 49.
Spain's Alvaro Quiros is also 11-under, with American Bryson DeChambeau and Australia's Lucas Herbert on 12 under.
World number five DeChambeau has fired back-to-back rounds of 66 and is seeking a fourth win in his last nine events.
His card was damaged by three bogeys on Friday but an eagle and seven birdies - one following a superb iron from a dirt track to leave a short putt on the sixth - repaired the damage.
The 25-year-old has five PGA Tour wins but has never won a European Tour title.
"I thought yesterday getting it around not making a bogey was awesome, but today was even more impressive with three bogeys on the card and still shooting six under," the American Ryder Cup player said.
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.
The Emirates Golf Club venue is where Els won his first European Tour title 25 years ago. The South African is nine months away from being eligible for the Champions Tour but victory on Sunday would secure his 29th European Tour success.
"I like this place. I've had some really great times here," said Els, who last won at the European Tour's BMW International Open in 2013.
"I've had a good time. I've been a professional for a very long time and I've got one more year before I'm 50. I'm only 50 in October so I'll try and have a good year this year and just try and enjoy it.
"I think it might play a little tougher over the weekend and in the afternoons if the wind comes. But I think still just keep the foot on the pedal, try and make some birdies. There's still a lot of work to be 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.
Wales Bradley Dredge, Ireland's Shane Lowry and England's Jordan Smith are all eight under.