Watching Tiger Woods at Olympia Fields on Saturday reminded me of his Sunday display at the Masters.
On both occasions, his game completely deserted him when he needed to press on.
I was very surprised to hear him say afterwards that he thought he was swinging well, and that there were no holes here where he could use his driver.
I am sure that if he was really swinging well he would have found a way to bring his driver into play.
He was clearly annoyed by the distraction from the gallery on the first, but I think he was more shaken by his inability to convert birdie chances on those early holes.
After all, he has been dealing with noisy crowds for years.
Starting his third round at four under, Woods didn't need to do anything super-human today to stay in contention.
But he seemed unable to find or execute a strategy to get around this course.
The big question now is if this means Tiger is in a slump.
He says he has played seven events this year and won three of them, some slump!
But this will be the first time since 1999 that he hasn't held a Major title, and those are the standards by which he is judged. The pressure will be really on him now at the Open and US PGA.
I am sure that Jim Furyk will be sleeping much easier tonight knowing that Tiger isn't a factor.
Even five shots back would have been close enough for Woods to apply pressure on Sunday.
He could have gone on an early birdie blitz - like Nick Price today - and Furyk would have been unnerved before he had even hit a shot.
Now the only guys with the experience of winning a Major are five shots back, and that is probably too far back from them.
Vijay Singh's collapse was especially surprising to watch - he appeared to be thrown off his game after he just missed a birdie putt on 15.
Furyk had just holed a long one to go two shots clear and Singh never recovered. His shot selection went to pieces and his putting touch disappeared.
Singh is handed his ball after hitting into a fenced area at the 18th
The bogey-bogey-bogey finish was shocking for an in-form player who had been so good for 45 holes.
It also showed how quickly this course could bite you if your concentration slipped.
Among the Europeans, Justin Rose should be delighted with his debut.
The young Englishman has just started working with Belgian sports psychologist Jos Vanstiphout and it appears to have had a great effect on his mentall resilience.
To be one over par without really swinging well, and starting so badly on Thursday, is a real achievement.
Darren Clarke continues to suffer with his putting and it is a great shame. He is striking the ball magnificently only to miss chance after chance on the greens.
And the fact that Freddy Jacobson is the best placed European is probably not good news for the European Tour.
The young Swede has made no secret of his intention to try for the US Tour and his good display here will be bring that about sooner rather than later.
His loss would hurt our tour as he is a genuine character and a great talent.