The 34-year-old World No. 25 produced golf of supreme quality to card a tournament-best seven-under 65 and stood at nine-under par, one stroke clear of fan favourite Phil Mickelson, who covered the back nine in six-under 30, one shy of the tournament record.
A stroke further back at seven under came South Africa’s Louis Oosthuizen after he had a 69 while Bubba Watson of the United States was on six under after a 70.
Matt Kuchar (70) was on five under with four players — Hunter Mahan of the United States (68), Henrik Stenson of Sweden (70), Lee Westwood of England (72) and Padraig Harrington of Ireland (68) — all on four under.
Hanson, who played with Mickelson in the first two rounds, is one of the quiet men of golf, but after bogeying the first he made all the right sounds as he rattled off eight birdies, including the last two holes, to leap up the leaderboard.
It is only the Ryder Cup player’s second Masters, having missed the cut last year.
Asked what he would need to manage on Sunday he replied: “Emotions, of course. That’s going to be the biggest thing.
“This is kind of a new situation to me, being in the spotlight like this, and playing the last group.
“So it’s going to be about controlling my emotions and trying to be in the present and trying to play the same kind of golf that I’ve been doing today.”
With only a one-stroke edge over three-time Masters champion Phil Mickelson, Hanson said it does not feel like he has any advantage.
And after playing alongside Mickelson for the first two rounds this week, Hanson knows the 41-year-old American left-hander is beloved by the Augusta National spectators who will watch them together again in Sunday’s final round.
“I know a one-shot lead over Mickelson is pretty much nothing,” Hanson said. “He would be the big-time favourite to win. I see myself as a little underdog.”
The Swede birdied five of the last seven holes and birdied both front nine par-5s, the second and eighth holes, plus the par-4 seventh.
“This course is very challenging,” Hanson said. “To shoot 65 around here, to shoot 31 on the back nine, is something you dream about.
“The last four or five holes, when everything seemed to be going right, the ball seemed to find the hole some way. People call it the zone or that peak performance, and I think I was pretty close to that.”
Mickelson refused to accept the favourite’s role conferred upon him without heaping praise upon Hanson.
“He was hitting shots right on the pin and he was making a lot of putts and I had to make something happen just to hang close to him,” Mickelson said.
“I felt like I had to birdie to keep pace. He played phenomenally. It’s very difficult to follow those kind of birdies and I felt fortunate to be able to get a couple and to stay within one.”
The final Sunday pairing at Augusta National has produced 19 of the past 21 Masters champions, although last year’s winner Charl Schwartzel of South Africa was an exception.
Augusta crowds have cheered Mickelson to green jackets in 2004, 2006 and 2010 and Hanson tried to use the support for his playing partner to bolster his own emotions.
“Walking these fairways with Phil will be amazing,” Hanson said. “The crowds are so much behind Phil. They love him and I understand why.
“I played with Phil the first couple of days and I was trying to use that as a bit of motivation for me as well. I tried to stay pretty close to him the first couple of days and feed off it a little bit.
“I’m just going to try to enjoy it. We’ve played a lot of golf together and with all the support behind him, hopefully it can feed off a little bit toward me as well.”
Mickelson and Hanson also played against each other in singles at the 2010 Ryder Cup, where Mickelson took a 4-and-2 triumph.
“He started off with four straight birdies and just killed me,” Hansonsaid. “I had no chance.”