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Spieth drops a shot with a very wayward par putt from 10 feet at 15. It is a tough green and has given very little to players throughout today. The Masters champion drops back to two under.

Tiger's woes continue. After all the sand-related problems, he misses a short putt for double bogey. "Oh my god, what are you doing?" someone cries from the crowd. He's falling apart is the simple answer. He is 10 over now. Only Rich Berberian Junior's score of 13 over is worse today.

Rickie Fowler is not faring much better than Tiger. He is nine over after another bogey.

There were 36 players under par about 45 minutes ago. There are now only 28.

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Justin Rose joins the sand party by plugging his ball in a different bunker at 15 to the one in which Day is buried. Chambers Bay is getting nasty.

Tiger goes from one bunker to another at 14, plugging in the second. The only way this could get worse for him is if the Sarlacc is waiting for him when he gets there. He is seven over at the moment. What he emerges from this hole at, who knows?

Jason Day, who is four under, doesn't fare much better on 15 by finding the bunker to the left of the green, in which his ball becomes nearly submerged in sand. With the flag at the front of the green his chances of getting near are slim to none.

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How much difference does a top-notch, knowledgeable caddy make to a player? Jack Nicklaus and Angelo Argea, Tiger Woods and Steve Williams, Happy Gilmore and that bearded hobo. The world's best have always trusted in a top bag man and Jordan Spieth may just have the stellar shot-sage on his side this week.

The Masters champion's man Michael Greller grew up near Chambers Bay and knows the course well, an advantage that could be crucial on this testing and somewhat mysterious links.

For an insight into the challenge Chambers Bay poses, have a watch of this guide from BBC Sport's Caroline Rigby.

Jordan Spieth's caddy Michael Greller dishes out some good advice to his player, who steps up and plants his 10 foot putt straight into the hole at 14 for a par. Spieth remains three under.

It must be that bit more daunting at the moment for Tiger to be stood in front of the 14, with all its sandy traps, and consider what to do. He smacks his tee shot about 60 yards wide of where he was aiming and finds the dust.

Jason Day simply refuses to hold back. He gives everything a belt. It serves him well, though, as a lovely iron shot puts him about six feet from the hole at 14 and with a good chance of going to four under. Tiger makes it three consecutive bogey fives at 13 to go seven over. It is painful to watch.

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Jordan Spieth beats the sand at 14 with a superb drive that plants itself bang in the middle of the fairway. Brian Campbell sends a long-range putt scampering towards the second hole but it pulls up, denying him a share of the lead.

The wind is causing chaos now. Fowler and Oosthuizen fail to put enough on their second shots at 13 and the balls end up rolling back down the slope to a bunker. Tiger hacks out and then plants his next shot on the green. It is a good third, but it should have been his second.

Justin Rose sends a 15-footer on its way at 13, looking for a birdie. It looks good as it sets out but ends up right of the hole as the green fails to yield the expected turn.

Meanwhile, Spieth is having no trouble. He makes it a hat-trick of successive birdie threes to go to three under with five to play.

Tiger belts a drive at 13 but misses the widest fairway on the course.

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There is no conviction whatsoever in the shortish putt Tiger offers at 12. That certainly wasn't the fault of the surface, just a sheer misreading of the contours to send the ball a good couple of inches past the hole right to take him to six over. The American has an awful lot on his mind right now. And most of his thoughts will be as gloomy as his outfit.

Justin Rose hits a great first shot at 13 and follows it with a belting second to hit the green and give himself a putt in the teens for birdie. He's been very steady so far the Englishman. All pars but for two birdies and a bogey.

Oh dear Danny Willett. He has a foot and a half for a bogey at five and misses. A double takes him back to even.

Tiger looks lost. He stands, hands on hips as he figures out how to get his ball back off a path at the 12th and back on to the fairway. Four practice swings give his iron a good scuffing before he chips up and onto the green, with a long birdie putt. From that position it is a job well done.

Oh, Rickie Fowler! He hits a storming drive at the par-four 12 - the hole that has already produced a string of eagles - and he comes within an inch or two of a hole in one as his ball reverses from the back of the green to dribble just past the hole. Almost a hole in one. On a par four! He settles for a much-needed eagle to improve to seven over.

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Ben Martin goes to five under with a superb putt across the second green. It is uphill, into the wind but he hits it firm, true and home. Joint leader, sir.

Meanwhile, Spieth has a second birdie on the bounce at 12 to go two under. Moves are being made.

Tiger at the 11th. Out of the rough on the edge of the fairway. He gets it up and out and on to the green but still with plenty to do. It is a birdie chance but it would have to be a superb putt to get him there.

Justin Rose uses the slopes well at 12 to make amends for a slightly wayward drive and give himself the chance to putt for birdie.