Zach Johnson ended a lively first day of the 142nd Open Championship with a one-shot lead as debate raged over the set-up of Muirfield.
Opinion was divided over whether the East Lothian links was set up fairly as only 20 of the 156 starters managed to break par in firm, dry and lightning-fast conditions caused by the prolonged spell of hot weather.
Ian Poulter labelled some of the pin positions as "a joke", while Phil Mickelson was another high-profile player to criticise a parched course baked by non-stop sunshine and temperatures approaching 30 degrees.
But the R&A insisted the course was "far from unplayable", as Johnson proved when he returned a classy five-under 66 to claim a narrow lead over 1998 champion Mark O'Meara and Spaniard Rafael Cabrera-Bello.
Tiger Woods overcame an uncertain start to post a commendable 69 over the most difficult period of the day, but Rory McIlroy cut a forlorn figure after slumping to a lacklustre 79 that leaves him a doubtful starter for the weekend.
The early starters clearly had the optimum scoring conditions, with Miguel Angel Jimenez first to hit his straps when he birdied four of the first five holes and added another at nine to turn in 31.
The putts, like the greens, dried up for the veteran on the inward half, but a 68 earned him the clubhouse lead for a few minutes until his compatriot Cabrera-Bello completed a six-birdie, two-bogey 67.
But both were surpassed by 2007 Masters champion Johnson, who followed a birdie at the third with an eagle at the fifth before hitting the top of the leaderboard with further birdies at six and seven.
The American continued to wield a hot putter as he nailed another birdie putt at the 12th before making his only mistake of the round at 14, but he parred safely in to remain at five under.
Johnson was briefly overtaken by inspired Shiv Kapur, who made light of playing in the fourth-last group out as he birdied six of the opening seven holes in a sizzling outward 30 to match the weather.
But a double-bogey at the 10th halted the Indian's momentum, and he dropped another shot at 14 before signing for a 68 that matched the earlier efforts of Jimenez, Dustin Johnson, Brandt Snedeker and 1996 champion Tom Lehman.
Another former winner, Todd Hamilton, was also in contention on two under alongside Mickelson and Woods, who snap-hooked his opening tee-shot into an unplayable lie and did well to limit the damage to a bogey.
The world No 1 remained one over at the turn, but he surged up the leaderboard with three birdies in four holes and hit back from a bogey at 14 with his fifth birdie of the day at the long 17th.
Former Masters champion Angel Cabrera was another veteran to shine on the opening day as he also fired a 69 along with 19-year-old Jordan Spieth, who pipped Zach Johnson to the John Deere Classic title last week.
Poulter aired his frustrations after dropping four shots in the last five holes to close on one over alongside an erratic Lee Westwood, while US Open winner Justin Rose managed only one birdie at 17 as he opened with a 75.
But a clearly out-of-sorts McIlroy faces a huge task just to make the halfway cut after his concentration, and his all-round game, unravelled on the back nine.
The world No 2 hit back from bogeys at four and five with a birdie at the seventh, but he bogeyed the 10th and 11th and scrapped his way to an ugly double-bogey six at the next.
McIlroy lifted his spirits with a birdie at 13 but his day was summed up at the 15th, where his putt from the front fringe raced past the pin and rolled into a bunker at the back of the green.
Another six was followed by two closing bogeys which added up to a 79, the same score as Sir Nick Faldo, while Luke Donald also doubled the 12th and then ran up a triple-bogey seven at 14 as he failed to break 80.