Bill Haas claimed the clubhouse lead in the 78th US Masters as the shortest hole at Augusta National had a major impact on two players attempting to enter the record books.
Haas carded an opening 68 to finish four under par, two shots ahead of Gary Woodland and KJ Choi and rookie trio Kevin Stadler, Jonas Blixt and Jimmy Walker.
Defending champion Adam Scott had been four under par after a flawless opening 11 holes, with one of his birdies coming on the par-four 10th where he sealed victory on the second hole of a play-off with Angel Cabrera last year.
But the Australian - aiming to join Jack Nicklaus, Nick Faldo and Tiger Woods in winning back-to-back titles - then dumped his tee shot on the 12th into Rae's Creek in front of the green to run up a double-bogey five, before three-putting from long range for par on the 13th and 15th.
Three groups ahead, Miguel Angel Jimenez was also four under after 10 holes as he looked to become the oldest winner of any major championship, Julius Boros being 48 years four months and 18 days when he won the US PGA Championship in 1968.
But the 50-year-old Spaniard then dropped a shot on the 11th and also found water off the tee on the 12th to card a double bogey.
Scott had made the ideal start to the defence of his title as the 78th Masters got under way in perfect conditions, the 33-year-old making the most of seeing his tee shot on the first narrowly miss a deep fairway bunker by firing a brilliant approach to within three feet of the hole.
Scott duly holed out for a birdie a nd although he failed to birdie the par-five second after his approach found a greenside bunker, the world number two then picked up further birdies on the sixth, eighth and 10th.
Playing partner Matt Fitzpatrick got off to a nightmare start with a double-bogey six, the US Amateur champion driving into trees and then pitching over the green with his third shot.
However, the 19-year-old from Sheffield hit back with a birdie on the second and remained one over par until bogeys on the 13th and 14th.
Pre-tournament favourite Rory McIlroy had been in danger of dropping a shot on the first after spinning his approach back off the green, but almost holed his pitch and was left with a tap-in to save par.
The 24-year-old also made par on the second after finding the same bunker as Scott, but holed from five feet for birdie on the third and also birdied the fifth.
McIlroy fell back to level par after a bogey on the eighth and three-putt bogey on the 12th, but birdied the 13th to get back under par.
Scotland's Stephen Gallacher had been in outright second after a birdie on the ninth took him out in 33, but the debutant bogeyed the 10th, 11th and 12th.