SHANGHAI, Oct 27, 2012 (AFP) - Hanson, who led on 14-under par going into the third round of the flagship European Tour event in China, found a chilly overcast day with a shifting wind much harder for low scoring and followed his magnificent Friday round of 64 with a steady 70 to move to 16 under.
It enabled world number one McIlroy, playing alongside Hanson in the final group, to pull within one shot with a three-under par 69 to leave him on 15 under for the tournament.
The Swede was clearly relishing his battle with McIlroy and added: "It's just great also to play alongside Rory, and every chance you get to compete with the world number one it is just a fantastic thing to do."
McIlroy is two shots clear of South Africa's George Coetzee in third and a further two shots back to a group of six players that includes the English pair of world number three Luke Donald who carded a four-under 68 and number five Justin Rose (69).
McIlroy won at Lake Malaren last year when the tournament was an invitational and he would clearly like to triumph again now it has grown into one of the biggest prize money events on the European Tour.
"It would mean a lot if I could successfully defend here at Lake Malaren. It would be nice to win for a second time," McIlroy said.
With a $1.166 million cheque awaiting the winner, McIlroy also sees a chance to seize the European money list title to add to the US one he has almost certainly already secured with his wins in the US PGA and two FedEx Cup events.
"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," McIlroy said.
"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."
But first the 23-year-old from Northern Ireland has to get ahead of Hanson, who was happy with his steady day's work.
"The pins were a little bit more difficult today but I'm pleased as it was a good round of golf," said Hanson.
"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.
"But I do need to step up a bit more because if I don't I am going to have the world number one snapping right at my heels and if I'm not careful he could be going past me."
Nicolas Colsaerts, another Ryder Cup star, looked at one stage as if he was going to join them in Sunday's final group, but a disastrous finish of two consecutive double bogeys at 16 and 17 dropped him back into the pack.
In a matter of minutes the big-hitting Belgian had tumbled from being right in the mix at 14 under par to being back in the chasing pack at 10-under par and in a tie for 10th place.
Also on that mark was 2010 US Open champion and Ryder Cup star Graeme McDowell, who had a welcome return to form with one of the best rounds of the day, a six-under par 66.
On a good day for Asia's golfers, Thongchai Jaidee of Thailand carded the low round of the day with a seven-under 65 while local boy Wu Ashun thrilled the vociferous Chines galleries with a hole-in-one at the 156-yard sixth hole on his way to a 69.
Leading scores on Saturday after the third round of the BMW Masters at Lake Malaren Golf Club, Shanghai:
(Par 72, 6,706 yards)
200 - Peter Hanson (SWE) 66-64-70
201 - Rory McIlroy (NIR) 67-65-69
203 - George Coetzee (RSA) 69-68-66
205 - Michael Hoey (ENG) 67-70-68, Charl Schwartzel (RSA) 69-68-68, Luke Donald (ENG) 70-67-68, Justin Rose (ENG) 68-68-69, Alexander Noren (SWE) 68-68-69, Shane Lowry (IRE) 72-64-69
206 - Graeme McDowell (NIR) 69-71-66, Ross Fisher (ENG) 69-69-68, Paul Casey (ENG) 70-68-68, Martin Kaymer (GER) 68-69-69, Louis Oosthuizen (RSA) 68-69-69, Nicolas Colsaerts (BEL) 69-68-69
207 - Thongchai Jaidee (THA) 70-72-65, Ian Poulter (ENG) 70-69-68,
208 - Edoardo Molinari (ITA) 68-71-69, Soren Kjeldsen (DEN) 72-66-70, Jamie Donaldson (WAL) 62-74-72
Selected:
210 - Lee Westwood (ENG) 70-69-71, Ashun Wu (CHN) 71-70-69, Liang Wenchong (CHN) 69-69-72, Robert Karlsson (SWE) 71-64-75.
212 Jose Maria Olazabal (ESP) 67-72-73