Hanson, who won the KLM Open last month, was at 16-under 200 at the Lake Malaren Course. He was wary of McIlroy, who shot a 69.
"I feel myself very lucky to be in this position and hopefully I can stay ahead of him because it is going to be a tough one considering the way he is playing, so I need to play a little bit better than I did tomorrow to have a chance of beating him," Hanson said. "But if I were to win this event it would be massive and this is the start of a big stretch coming up now, so it's just nice to find a bit of form and see yourself up there, and having a bit of a chance of winning the title.
"But I do need to step up a bit more because if I don't I am going to have the world No. 1 snapping right at my heels, and if I'm not careful he could be going pass me."
McIlroy, chasing a fifth title this season, won the exhibition Shanghai Masters tournament on the same course last year.
"It would mean a lot if I could successfully defend here at Lake Malaren, even though this year's event is now on the European Tour, so it would be nice to win for a second time," he said. "What also would be most pleasing is that I will come into these last few weeks of my year trying to wrap up the Race to Dubai No. 1 title.
"I've put myself into contention this week and (if) I'm to finish this one off that would give me a nice lead going into my last three events. So that would more pleasing than anything else as it would extend my lead over Justin (Rose) and Branden (Grace), so that when I do get to Dubai later next month I won't have to do much."
George Coetzee of South Africa (66) was in third at 12 under. Alexander Noren of Sweden (69), Michael Hoey of Northern Ireland (68), South Africa's Charl Schwartzel (68), Shane Lowry of Ireland (69) and the England pair of Justin Rose (69) and Luke Donald (68) were tied for fourth another shot back.