Steve Stricker shot a stunning bogey-free 63 to lead after the first round of the USPGA Championship and tie for the lowest ever round in Major history.
The American became the 23rd player to sign for that number in a Major and could have even gone one better, but he missed a 15-foot birdie chance on the 9th, his final hole.
While Stricker made serene progress to secure a two-shot lead from Jerry Kelly, Rory McIlroy endured a far tougher opening round.
The US Open champion found his ball resting against a thick tree root after an errant tee shot on the 3rd hole and injured his wrist when he decided to take on a risky recovery rather than chip out sideways.
He made a bogey five, but his participation in the tournament was thrown into real doubt by the injury. The Northern Irishman seemed to be in a lot of pain, but he soldiered on and with assurances from the physio that he wouldn't do any further damage to the wrist and treatment throughout the round, he battled to an admirable 70.
McIlroy went straight to hospital after his round and an MRI scan revealed that he'd strained the tendon. His management company ISM confirmed that he would rest the injury overnight and see how it felt on the range before his 8.35am tee time (1.25pm BST) before deciding whether to carry on.
The day's other big headline was Tiger Woods' opening 77; his worst ever opening round in a Major.
The former world number one started brightly and was -3 for his first five holes, but a trip into the water on the long par-3 15th, his sixth hole, resulted in a double bogey that proved to be the catalyst for a horror run of playing his final 13 holes in 10 over par.
Experience rose to the top of the leaderboard in the first round, with 2003 champion Shaun Micheel and Scott Verplank tucked just behind Stricker and Kelly on -4 and -3 respectively.
The European charge was led by Matteo Manassero, Anders Hansen and Simon Dyson, who shot 68s to lie in a tie for fifth. Luke Donald (70) and Lee Westwood (71) made solid starts, and defending champion Martin Kaymer battled to a 72.