Tiger Woods and Lee Westwood edged into contention after a topsy-turvy second day of the 142nd Open Championship.
The pair finished on two under par and then watched as the front-runners faltered to leave them one off the pace set by 49-year-old Miguel Angel Jimenez on another testing day at Muirfield.
The Spaniard carded a level-par 71 to inherit the lead, with Woods, Westwood, Sweden's Henrik Stenson and American Dustin Johnson in the chasing pack.
Jimenez, who broke his leg in a skiing accident in the winter, would become the oldest major winner if he triumphs on Sunday, beating the 48 years four months of American Julius Boros when he won the US PGA in 1968.
"Enjoy yourself, what you do in life - that's the secret - that's what I'm doing," he said.
"I feel relaxed, I play golf for a living and I've been doing the same thing for 25 years."
Jimenez, famed for his quirky warm-up routine and love of Rioja wine, refused to alter his routine just because he was leading the Open.
"I'm going to hit some balls, I'm going to have a nice cigar, have dinner with my girlfriend and with my sons and when the sun comes up tomorrow I will deal with everything," he said.
Rory McIlroy was unable to claw back ground on his opening 79 and carded 75 to miss the cut.
The 24-year-old admitted he used the second part of his round to practise after realising he was going to miss the cut and used his driver where possible to prepare for upcoming tournaments.
"It's the first time I've missed a cut at the Open, so it's obviously quite disappointing," he said. "But I have a clearer picture of what I need to work on and what I need to do to put things right."
England's US Open champion Justin Rose (75, 77) and former world number one Luke Donald (80, 72) also missed out on the weekend.
World number one Woods, chasing his first major since 2008, birdied the last for a 71, while Westwood made the early headlines with six birdies in his first 12 holes to take a share of the lead at five under before sliding back.
"It'll be a fun weekend. This course will be difficult," said Woods, who won the last of his three Opens on a similarly firm and fiery course at Hoylake in 2006.
Zach Johnson, the overnight leader, was still clear with five to play but dropped four shots for a 75 to end in a group on one under, with Scotland's Martin Laird (71), Spain's Rafael Cabrera-Bello (74) and Argentine Angel Cabrera (72).
American Ryan Moore, one shot further back, was the only other player at level par or better.
Northern Ireland's Darren Clarke, the 2011 champion, bogeyed the last to finish one over after a 71 which included a quadruple-bogey eight on the sixth after taking three to get out of a greenside bunker.
Also in the group at one over were last year's runner-up Adam Scott, the Masters champion, four-time major winner Phil Mickelson, former Masters champions Charl Schwartzel and Bubba Watson and England's Ian Poulter.
Poulter, who was scathing of the course set-up on day one, said there was only one "dicey" pin position - the 15th - on Friday, but insisted conditions were just as tough given the hot sun and drying wind, blowing from the east rather than the west.
"You've got to suck it up, I guess," he said. "It's the same for everybody. And unfortunately you've got to grind through it. You don't have another option, if you want to win to tournament.
"It's pretty wide open. It's easy to get on a bad spell on this golf course."
Defending champion Ernie Els ended in a logjam on six over alongside former winners Padraig Harrington and Sandy Lyle and Spain's Sergio Garcia.
Sir Nick Faldo, 56, back at the site of two of his three Open victories, shot 78 to end 15 over in his first Open since 2010.
Among the others to miss the cut were 63-year-old five-time champion Tom Watson, American Rickie Fowler and Italy's Wentworth PGA champion Matteo Manassero.