At one point, Singh let out a hearty laugh walking off the tee with Robert Garrigus and J.J. Henry. His golf wasn't the subject of the laughter. Singh hit into the water on the last hole and made bogey for a 74, leaving him in danger of missing the cut.
So ended a first round filled with plenty of action -- a record-tying score by a player hardly anyone knows, McIlroy breaking par for the first time at Sawgrass, 17 balls in the water around the island-green 17th and 33 rounds in the 60s.
Padraig Harrington followed an eagle with a double bogey. Michael Thompson made a hole-in-one.
But it all started with Castro, a 27-year-old who felt like he couldn't miss. His record-tying score was posted as players were on the practice range getting ready to tee off in the afternoon, making it tough to stay patient on a course that demands it. Woods was nine shots behind before he hit his first shot.
"I've seen that a lot, but not at this golf course," he said.
He did well to get within four shots. Woods, Webb Simpson and Ryan Palmer at 67 had the lowest round among those who played late, and they now turn around and get the morning conditions -- hopeful they'll be the same -- today.
McIlroy also played in the morning, in the same group as Masters champion Adam Scott (69) and Steve Stricker (67).
The 24-year-old from Northern Ireland had never made the cut or even broken par at The Players, but McIlroy figured it out on a gorgeous morning by dialing it back off the tee and letting his iron play take over. McIlroy never came seriously close to a bogey, and he didn't hit drive once on the front nine.
"When you hit the shots, it seems very simple," McIlroy said. "I had a lot of good shots out there, lot of iron shots that were 12, 15 feet away from the pin and I got myself a lot of looks for birdies. I adopted maybe more of a conservative strategy off the tee this year. But once you put your ball in the fairway that means you can be more aggressive into the greens. So it sort of balances itself out."
The Stadium Course has rarely looked so vulnerable with barely a trace of wind and some pins in bowls that allowed for good looks at birdie. Half the 72 players in the morning broke par.
But the punishment is never far away, as Scott Stallings discovered. He opened with five straight birdies to get everyone's attention, but after going out in 31, Stallings gave most of it back with a bogey, double bogey and a triple bogey on the 16th when he hit two balls into the water. He shot 40 on the back for a 71.
"It just goes to show about the golf course and really how volatile it is," Stallings said.
Castro hasn't discovered that yet. This was a day when everything went right.
He made three birdies early in his round on the back until making his tap-in birdies on the 17th and 18th. Then, he hit 3-iron into 3 feet on the par-5 second hole for an eagle and was 7-under through 11 holes. On the fourth, he hit his approach inside 2 feet for another birdie, and then he hit wedge to 18 inches on the sixth.
Castro had a birdie putt just outside 12 feet to break the course record, but missed it.
After his eagle on the second hole -- his 11th of the round -- Castro was reminded of a game he plays to try to birdie every other hole.
"When I eagled, I was like, 'Oh, now I'm 7 (under) through 11, so that's keeping ahead of that 50 percent mark.' But this is a different golf course," he said. "The golf course is much harder than most of the other times I've kind of taken that attitude."
Couples shot his 63 in 1992 in the third round. Norman opened with a 63 in 1994 when he went on to shatter the tournament record at 24-under 264. Along with joining them in the record book, Castro matched the record set by Billy Ray Brown in 1992 with his three-shot lead after one round.
Castro is not well known even in golf circles. His mother grew up in Peru and moved to America as a teenager along with her sister, Jenny Lidback, who played the LPGA Tour. He toiled in the minor leagues for five years after getting his industrial engineering degree at Georgia Tech.
Woods wasn't pleased with how he struck the ball, only with where he missed it. Despite missing six greens, he was left with straightforward shots to save par. The only blemish came at the end, when his 56-degree wedge came up heavy into the grain and failed to reach the putting surface.