American Brandt Snedeker claimed his place in Open Championship history to set a daunting clubhouse target at Royal Lytham & St Annes.
Snedeker added a brilliant 64 to his opening 66 for a ten under par total of 130, equalling the lowest score over the first 36 holes in Championship history and the lowest Open round at Lytham.
Sir Nick Faldo also shot rounds of 66 and 64 at Muirfield in 1992, while Tom Lehman's round of 64 on his way to winning here in 1996 was matched by first round leader Adam Scott.
Snedeker, who had been 25 over par for his previous three Open appearances, was two behind Scott overnight but wiped out his deficit in style with a flawless front nine of 30.
The 31 year old from Tennessee picked up shots at the first, sixth, seventh and ninth, before adding further birdies on the 11th and 12th to move four shots clear of the field.
He looked in danger of dropping his first shots of the week on the 15th and 18th, but saved par superbly each time to complete a remarkable 36 holes without a bogey on one of the most difficult courses on The Open rota.
Scott remained six under after seven holes with 1999 Champion Paul Lawrie five under after eight, while Tiger Woods was seven off the pace on three under.
World Number One Luke Donald had earlier carded four birdies in five holes from the fourth to be out in 31, but then fluffed a chip on the tenth to bogey and eventually signed for a 68 to lie two under.
That was considerably better than former US Open Champion Rory McIlroy however, who found five of Lytham's 206 bunkers and dropped six shots on those holes in a 75 that left him two over.
Four-time Major winner Phil Mickelson fared even worse with a 78 to finish 11 over, but England's Greg Owen looked to have found the ideal way to make the cut, holing his second shot to the 18th for an eagle two and a second consecutive round of 71. Owen also had an albatross on the par five 11th when The Open was last staged at Lytham in 2001.
Snedeker admitted he was aware of trying to keep a bogey off his card as he played the 18th, but not about joining Faldo in the record books.
"That was not even on my radar coming into Thursday morning, I was just hoping to make the cut," said the World Number 29, who missed the US Open recently after suffering a rib injury caused by coughing too much.
Asked about the turnaround in his Open form, Snedeker added: "The golf course is playing more Americanised now, it's soft with not a lot of wind, and I have a different mentality this time, I'm playing away from a lot of pins.
"I tried to just get the ball on the green all day, even if it was 100 feet away. When you're putting the way I have been the first two days you want to get it on the green as fast as you can."
Scott was not about to give up the chase easily however, picking up shots at the tenth and 11th to move within two shots of Snedeker on eight under par.
Woods also birdied the fourth and sixth to improve to five under, but World Number Three Lee Westwood carded nine straight pars on the front nine to remain three over.