Peter Hanson answered with four birdies on his last five holes, claiming some of those cheers for himself and taking the outright lead Saturday in the Masters with a 7-under 65, the lowest score of the tournament.
What a finish -- and it's all just beginning.
"Fortune favors the brave at times here," Padraig Harrington said.
"When you're leading a tournament, that's not the type of golf course you want to be on," he added. "You want to be on probably a boring golf course -- which this ain't."
That much was evident on a day filled with cheers from every corner, a prelude for a final round that would figure to favor Mickelson.
Hanson, a 34-year-old Swede playing in only his second Masters, has never been closer than seven shots of the leaders in his previous 17 majors. He goes into Sunday with a one-shot lead over Mickelson, who already has three green jackets.
Hanson passed his first test.
He was walking up the 14th fairway when he heard a commotion that shook Augusta. He knew what it was without looking -- Mickelson draining an eagle putt on the 13th hole, raising the putter with his right arm and slamming down his left fist to celebrate along with 15,000 of his best friends.
"I'm standing in the middle of the fairway and I feel him breathing down my neck a little bit," Hanson said.
Hanson followed with an approach into 2 feet for birdie, a 15-foot putt from the fringe on the 15th, a 30-foot birdie putt over the ridge on the 17th and one last birdie at the 18th with a shot that stopped inside 3 feet from the cup.
He was at 9-under 207.
"I've been watching this tournament since I was a young kid, and seeing Freddie Couples and the guys go and shoot 30 and 31 on the back nine is something you just dream about," Hanson said.
Mickelson shot 30 on the back and signed for a 66, putting him in the final group at the Masters for the fourth time in the last nine years. Lefty won the last three times he was in that spot.
"I love it here, and I love nothing more than being in the last group on Sunday at the Masters," Mickelson said. "It's the great thing in professional golf."
Mickelson gave the leaderboard some star power when so many others faded or, in the case of Tiger Woods, never came close to getting there. Woods now has gone 26 consecutive holes on the back nine at Augusta without a birdie. He had to settle for a 72 and was 12 shots behind, his largest 54-hole deficit ever at the Masters.
But he wasn't alone.
U.S. Open champion Rory McIlroy, who started the day one shot out of the lead, made double bogey from the trees on the first hole and it only got worse from there. He had three 6s on his card and went out in 42, finishing with a 77 that left him 10 shots behind. He played with Sergio Garcia, who shot 75. Neither made a birdie until No. 12, and they hugged each other on the green to celebrate.
Fred Couples, at 52 the oldest player atop the leaderboard going into the weekend at Augusta, bogeyed his first two holes and tried to stay in the game. He wound up with a 75 and was seven shots behind.
A win would give Mickelson his fourth green jacket, same as Woods and Arnold Palmer.
But this is far from a two-man race.
Former British Open champion Louis Oosthuizen rode his sweet swing to a 69 and was only two shots behind. Bubba Watson birdied the last hole for a 70 and was three shots back, followed by Matt Kuchar, who joined Mickelson as the first players in 13 years to birdie the 18th hole each of the first three rounds.
The group at 4-under 212 included Lee Westwood (72) and Harrington, who shot 68 and summed up what awaits on Sunday.
"It's not the player that plays the most consistent that wins at the Masters. The player who plays probably some of the most exciting golf wins at the Masters," Harrington said. "It's not really a contest of fairways and greens. It's a bit more flamboyancy in it. You only have to look at the way Phil has won some of his majors. You've got to take on golf shots."
And to think Mickelson almost lost this Masters on the opening day.
With a lost ball and a triple bogey on the 10th hole, he was 4-over par through 12 holes on Thursday and hitting the ball in places even he had never seen at Augusta. Only his short game saved him that day, and he escaped with a 74.
He has been on the move ever since, and Lefty was at his best on Saturday.
If there was one shot that showed why he has an imagination unlike others, it came from behind the green on the par-5 15th. Moments earlier, Hanson was in about the same spot and played a conventional bump-and-run up the slope to a green that runs quickly toward the hole. Hanson went just over the green, and had to make a 15-foot putt.
Mickelson took out his 64-degree wedge -- he carries that club for moments like this -- and played a full flop shot that landed softly and trickled to 4 feet below the cup for a birdie.
How tough was the shot? Even Mickelson said it was risky.
"It was possible to slide underneath it, so I leveled out my weight a little bit so that I would not take too deep a divot and the ball popped up nicely," Mickelson said, describing the shot as if giving a clinic.
Hanson was on the 16th hole when all this unfolded.
"To be honest, I never saw that high flop shot from there," he said. "He's just amazing with the wedge and the way he plays those shots. When I ended up in that same spot on 15, I just sought the bump-and-run and get it past the hole and leave myself an uphill putt. He goes up and just hits a full swing and goes straight up in the air."
But it was a lesson for Hanson, especially for the final round: Don't watch, just play.
"He has a few shots around the green that I'm not even close to," Hanson said. "I just have to play my game and work around this golf course the absolute best I can."
First, he has to get through the night. Hanson expects that sleep won't come easily -- not when you're in the lead for the first time in a major, with a green jacket on the line.
He has quietly risen to No. 25 in the world ranking, with a pair of top 5s in the World Golf Championships and a runner-up finish at the Qatar Masters. Hanson also has spent time in good company. He started working in the offseason with coach Gary Gilchrist, who also teaches Yani Tseng, the No. 1 player in women's golf.
The last time he was in a twosome with Mickelson was at Celtic Manor, and timing could not have been worse. Mickelson had just set an American record for most losses in the Ryder Cup, and he had not contributed a point all week.
"He came out so hungry and desperate to win," Hanson said. "He started off with four straight birdies. So I had no chance."
It's up for grabs Sunday -- but not for everyone.
The biggest surprise was McIlroy, who has been flawless for the last six months and was poised to seize control of this major when he started out just one shot behind. With two double bogeys and a 42 on the front, his Masters effectively was over.
"Seems like every year I come here, I throw a bad nine holes out there," McIlroy said, referring to his 43 on the back nine of the final round last year when he lost a four-shot lead.
As loud as it was, Woods rarely heard it so quiet.
He missed out on all the action by playing so early -- he was done about the time the leaders teed off. And he did nothing to make anyone cheer. For the second straight round, Woods failed to birdie any of the par 5s. In his previous 17 years at the Masters, he had gone birdie-free on the par 5s only twice.
Woods has made only one birdie all week on the back nine -- the first hole he played, No. 10, on Thursday.
"I unfortunately did not play the par 5s very well today," Woods said. "I'm telling you, it was just so close to being a really good round of golf."