Stenson produced eight birdies in a bogey-free 64 to move to 12-under par on day two of the season-ending event at Jumeirah Estates.
Spain's Alejandro Canizares (67) was at 11 under, while three shots further back were France's Victor Dubuisson (66), last week's Turkish Open champion, and Australia's Marcus Fraser (69).
However, Justin Rose (67), second in the Race to Dubai, and Ian Poulter (68), fourth, lost ground to Stenson to be tied at 7 under.
Graeme McDowell, third on the money list, also carded a 68 to be eight strokes adrift of Stenson on 4 under.
"They are chasing me as good as they can, and I know neither one of the guys are going to back down, so it is better I keep my foot down and my head down and try and keep the momentum going," Stenson said.
Stenson has yet to win on the European Tour this year, and would dearly love to end that run to wrap up the Race to Dubai in style.
"I'm in a great position to have a shot at winning this golf tournament after two rounds, so hopefully I can be there on Sunday afternoon," he said.
"The key for me this summer was that I have been up (the leaderboard) so many times, and when I needed the putts to drop they did in Boston (Deutsche Bank Championship) and when I played really well to win in Atlanta (U.S. Tour Championship).
If Stenson were to win the Race to Dubai he would join Robert Karlsson (2008) as the only Sweden-born players to earn the European Order of Merit.
U.S. Open champion Rose says it is becoming increasingly difficult to catch Stenson.
"I thought that 5-under par would be good enough for me to just stay in the tournament, which I am happy about," Rose said. "But then this golf course seems really tailor-made for Henrik. He just seems to be able to take advantage of all the par-5s, and he's playing really, really well. It will be tough to catch him."
Defending champion Rory McIlroy shot a 5-under 67 that included a 14th-hole eagle, to be tied for ninth on 6 under.
"It's nice to know going into the weekend you still have a chance to win the golf tournament, and that's the stage I've been trying to get to for the last few months," he said. "I finally feel like I've got to the stage now where I can contend week-in, week-out."
Asked to rate his ball-striking at the start, middle and end of the year, McIlroy replied, "2, 5 and 8, so it's getting up there."