Ernie Els staged a remarkable recovery from a poor start to put himself in contention for a third US Open title, 15 years after he collected his second.
The South African bogeyed three of the first five holes in his third round to slump to seven over, but he responded in style with birdies at seven, eight and 12.
Els then pitched in from 50 yards for an unlikely eagle at the long 17th, and a closing par capped an impressive two-under 68 - his second sub-70 round of the week.
"I'm in a much better mood now than I was on the sixth tee," said Els, just three behind leader Graeme McDowell. "To come back and play the last 12 holes in five under is quite amazing.
"The shot at 17 is what dreams are made of -- a shot like that in a US Open. "It's one of those one in a thousand shots.
"Even if I'm within four shots that's a great chance. I think if you get it into the red numbers, you'll win this tournament.
"Experience helps around here," he added. "For some reason I'm patient again this week."
But while Els was jubilant, Phil Mickelson found little to celebrate on his 42nd birthday as he posted a 71 which left him at eight over for the week.
"It's been a long, difficult day, even though it's my birthday," said the left-hander, who was given a rounding rendition of "Happy Birthday" by the fans around the 18th green.