Jordan Spieth is once again the man to catch at Augusta, a superb 66 putting the reigning champion two clear of the field on day one of the Masters as world number one Jason Day endured a late collapse.
Spieth set the tone for a wire-to-wire victory 12 months ago with an opening 64, but his latest effort was arguably even more impressive on a day when occasional gusting winds made scoring tricky on Thursday.
The 22-year-old's clubhouse lead appeared to be under serious threat when Day turned in 31 with the aid of an eagle at the second, but the Australian then dropped five shots in three holes from the 15th - finding water off the tee on his way to a triple-bogey six at 16 - and signed for a level-par 72.
By contrast, the unflappable Spieth, who has yet to finish lower than second at Augusta, was able to keep a bogey off his card as he equalled the lowest first-round score by a player looking to defend the Masters.
Danny Lee and Shane Lowry carded 68s to share second at four under, while Rory McIlroy followed Day's lead in suffering late on - dropping shots at 16 and 18 to sit four adrift in a tie for ninth.
Spieth's form in recent weeks has been no more than modest and he was forced into a late equipment change on the eve of this tournament when he cracked his driver.
However, the Texan looked back to his clinical best after going out among the earlier starters as he set a demanding target that would not be matched.
A host of precise approach shots enabled Spieth to pick up three birdies on each nine, while he also demonstrated strong powers of recovery when rescuing unlikely pars at 11 and 16 after errant tee shots.
Day's work over the first nine was more spectacular and he almost holed his second at the par-four ninth, yet a three-putt at 15 triggered a dramatic slump that left the US PGA champion with much to do.
As Day faltered, McIlroy surged into contention with an eagle at 13. He also hit the par-five 15th in two en route to a birdie, before three-putting 16 and giving another shot back at 18, where he found a plugged lie in a greenside bunker.
Lee and Lowry took contrasting routes to a share of second. While Lowry's best work came early, taking him to five under through eight, Lee came back in 33 after a steady outward nine.
Sergio Garcia, Soren Kjeldsen and a trio of Englishmen - Ian Poulter, Justin Rose and Paul Casey - shared fourth at three under, the latter playing alongside Spieth and amateur Bryson DeChambeau, who made 16 pars in his 72.
Two-time Masters winner Bubba Watson was three under through eight, but then bogeyed the ninth before coming back in 41 to sit nine off the pace at three over.
Others to struggle included 2013 champion Adam Scott, who shot 76, and world number five Rickie Fowler (80).
An eight at 13 represented a particularly painful experience for Fowler, while four-time major winner Ernie Els began his 80 with a scarcely believable nine - the worst score recorded at Augusta's opening hole - following a staggering six-putt from close range.