World number 267 Roberto Castro was the surprise leader after the first round of the prestigious Players Championship, but the top two players in the rankings were ominously poised at Sawgrass.
Castro carded an eagle and seven birdies in a nine-under-par 63 which matched the course record set by Fred Couples in 1992 and equalled by Greg Norman two years later.
However, world number two Rory McIlroy shot a flawless 66 to share second place with former Masters champion Zach Johnson, while Tiger Woods was set to do the same until his only bogey of the day on the 18th after failing to get up and down from over the green.
Woods, who replaced McIlroy at the top of the rankings earlier this year, had never had a bogey-free round in 55 previous attempts in the tournament, but at least carded a five-under 67, his first sub-70 opening round in the £6.1million event, which offers more than £1million to the winner.
McIlroy had reaped the benefits of a conservative approach after missing the cut in his previous three appearances in golf's 'unofficial fifth major' with a scoring average of 74. Starting from the 10th, McIlroy carded five birdies in a back nine of 31, including at the treacherous par-three 17th after a superb approach to seven feet on the island green.
He could only find one more birdie coming home - pitching to two feet on the par-five second - but also saved par from short of the green on the fifth and from a greenside bunker on the eighth.
With scoring conditions almost perfect for the early starters, Steve Stricker, Casey Wittenberg and Hunter Mahan all finished five under and were joined by Woods, Webb Simpson and Ryan Palmer. Sergio Garcia and Padraig Harrington were five off the lead after rounds of 68, while Lee Westwood matched the 69 of Masters champion Adam Scott.
The most remarkable round of the day came from Westwood's Ryder Cup team-mate Peter Hanson, who started from the 10th with a double bogey and took eight on the 18th, but also had seven birdies and an eagle in a two-under 70.
Vijay Singh, who on Wednesday filed a lawsuit against the PGA over its handling of his anti-doping case, finished two over after a 74, one shot better than Ian Poulter who wrote on Twitter: "Not the best day in the office. Followed by a urine sample in a cup for our drug friends. It's ok I haven't taken any horn juice lately haha."
That was a reference to the deer antler spray Singh admitted to taking in January which was said to contain a banned substance.