Simon Wakefield matched the low round of the day with his 6-under 66. That moved him into second place at 14-under-par 202. Two-time European Ryder Cupper Thomas Bjorn moved into third place with a 4-under 68. He stands at 12-under-par 204.
Jean-Francois Lucquin stands alone in fourth place at 11-under-par 205 after a round of 69. Eddie Lee, who played in the final pairing with Els, is one stroke further back at minus-10 after struggling to a 1-over 73.
Els opened his round with a birdie on the par-4 first for the third straight day. The South African tripped to a bogey at the fourth, his first bogey since his seventh hole of the opening round.
The 35-year-old recovered with a birdie at the seventh. Els made it two in row as he birdied the eighth at Tomson Shanghai Pudong Golf Club to move seven strokes clear of Bjorn.
Els, the owner of 20 European Tour wins, bogeyed the ninth after his drive found water, but came right back with a birdie at 10 to get back to minus-17. He faltered to another bogey at the 12th and his lead dropped to four strokes.
The two-time U.S. Open champion rebounded with a birdie on the 13th, his third in three days on that hole. Els converted a birdie putt on No. 14 to get to 18 under, five shots clear of Wakefield.
Els parred his next three holes before a birdie on the par-5 18th kept him five clear of Wakefield, who birdied the same hole.
'I have to be satisfied, but today was quite a difficult day here and there,' said Els, who won the Dubai Desert Classic and Qatar Masters in back-to-back weeks earlier this year. 'Friday I was right on, but today was a little off, but all in all I have to be pleased to be 19 under after three rounds.
'It's nice to have a lead, but you have to watch out. The boys are going to be coming hard and there were a couple of good scores today. I have to play sensibly and aggressive when I can.'
Wakefield climbed into contention with a stellar back nine. The Englishman played the opening nine at minus-1 with two birdies and a bogey.
Around the turn, Wakefield converted a birdie putt on the 10th to get to minus-10. After a pair of pars, the 31-year-old ran off three consecutive birdies from the par-five 13th to jump to 13 under.
Wakefield's 3-foot birdie putt on the 18th briefly got him within four of Els, but the South African also birdied the last for a five-shot cushion.
'I am very pleased even though it was a day of two halves really,' Wakefield said. 'I got off to a pretty nervy start, but I tried to keep a smile on my face all the way around because there were a few shots that I did not hit particularly well, but got good results. It is always nice to be in the last group on the final day. I hope I am not too intimidated by Els, but I am just going to enjoy it and see what happens.'
Luke Donald, Soren Hansen and Jeev Milkha Singh share sixth place at 9-under-par 207. Irishman Peter Lawrie and Frenchman Jean Van de Velde are one stroke further back at minus-8.
Miguel Angel Jimenez, the defending champion, is well off the pace at 4-under-par 212 after a third-round 69.