Defending champion Danny Willett and Rory McIlroy both produced battling performances on a highly eventful first day of the Masters, but still found themselves well adrift of inspired leader Charley Hoffman.
Hoffman defied swirling winds which gusted up to 35mph at Augusta National to card nine birdies and two bogeys in a stunning 65, 10 shots better than the field average.
That gave the Las Vegas-based 40-year-old the largest first-round lead in the Masters since 1955, with compatriot William McGirt his nearest challenger four shots back on three under.
Lee Westwood, who finished runner-up to Willett last year, led a strong European challenge on two under after five birdies in a row from the 13th in his 70, with compatriots Andy Sullivan, Matt Fitzpatrick and Justin Rose all one under.
Spain's Sergio Garcia also finished one under, with McIlroy, Soren Kjeldsen, Thomas Pieters, Paul Casey and Shane Lowry on level par.
World number one Dustin Johnson withdrew just moments before he was due to tee off, the US Open champion failing to recover from a back injury suffered in a fall at his rented house on Wednesday.
McIlroy had been three over with six holes remaining but birdied the 13th, 15th and 16th, while Willett recovered from being three over after two holes, aided by an eagle on the 13th.
"When I was stood on the third tee, if someone had said I would shoot 73 I would have ripped their hand off, walked up the hill and gone inside and had a cup of tea," Willett said.
"It was a less than ideal start, not what I had envisaged the last 12 months starting out my defence, but I fought back really well, dug my heels in and hit some really good golf shots."
Fitzpatrick was three under par when he reached the 18th tee, but was distracted by spectators leaning over the ropes to get a better view and pulled his drive into the trees.
"I just didn't really feel comfortable over the tee shot," said Fitzpatrick, whose drive travelled just 166 yards.
"My low one's lower than everyone else's, so I can actually kill someone at head high. I should have backed off it and got everyone to move."
A three-putt from long range compounded the error and resulted in a double-bogey six, but the 22-year-old still outscored playing partner Jordan Spieth by four shots.
Spieth held a five-shot lead with nine holes to play 12 months ago, only to follow dropped shots on the 10th and 11th with a seven on the par-three 12th after hitting two balls into Rae's Creek.
And although the 23-year-old managed a solid par on the same hole on Thursday, he ran up a quadruple-bogey nine on the 15th after spinning his approach off the green into the water.
Pieters had threatened to set a daunting target when he raced to the turn in 32 and also birdied the 10th to reach five under par.
However, the 25-year-old Belgian - who won a record four points from his five matches in Europe's defeat at Hazeltine - then bogeyed the 11th and double-bogeyed the 12th after finding water off the tee.