Why do they do it? The Ryder Cup causes just as much pain as exultation. Grown men, with millions of pounds lying in the bank, have been reduced to wimpish nincompoops. Others have responded to the challenge by delving deep into their reserves to produce exceptional shots that are now part of sporting folklore.

Colin Montgomerie recalls his debut in the event - at Kiawah Island in 1991 - as "miserable," while Philip Walton, even in his moment of triumph as the kingmaker of Europe's win at Oak Hill two years ago, confessed he had no feeling in his legs walking up the 18th fairway. "They were like jelly," he recalls.

The Ryder Cup is a nerve-wracking experience, with nowhere to hide. And the pressures are getting greater all the time. That old adage of "cometh the hour, cometh the man" has a special significance in the Ryder Cup. Back in 1989, it was Christy O'Connor Junior's turn. His two-iron approach to the 18th at The Belfry finished just three feet from the hole. Fred Couples, his opponent, pushed his nine-iron approach to the right of the green. O'Connor won by one hole and had played his part in keeping the trophy in Europe.

Next week in Valderrama you can bet your bottom dollar that another unsung hero will emerge. O'Connor is not alone a former Ryder Cup hero, but is also one of the foremost golf course designers in the world today. As such, he's ideally suited to name the crunch holes for next week's encounter.

"The course is an awful lot like Augusta, with the stimpmeter reading possibly as high as 13 1/2 which makes ball positioning on the greens absolutely vital," says O'Connor, who has chosen four holes - the seventh, the ninth, the 12th and the 16th - as the ones of utmost importance.

"A number of other holes did enter my mind. The 17th speaks for itself. However, you can't make up your mind whether or not you can reach the green until you drive the ball. You have to hit the perfect tee-shot for the green to be on in two. The 15th is a hell of a par three, with no shot if you miss the green left. You have to draw the tee-shot in. And it is easy to come unstuck on the 18th, where length is no advantage. Also, you don't see your tee-shot finish there, something which is always a little disconcerting.

"Still, I have chosen the four holes which I believe - in a matchplay situation like the Ryder Cup, with all the adherent pressure involved - will be the crunch holes in the match."

Seventh hole

461 yards Par 4

"The Corridor"

This is a hole that will suit Tiger Woods a lot, as it demands accuracy and length off the tee. Originally, it was designed as a par five and it needs an excellent drive. The bigger the better. You don't need a terribly long iron in (possibly four, five or six), but there is a line of bunkers close to the front edge and the green's size and shape means the approach shot demands a great deal of precision. There isn't much margin for error. It was originally designed to take a very lofted approach shot, a wedge or nine iron, so it is an exceptionally tough shot in its current guise.

The green is very, very quick back to front and is also undulating. I would say that anyone who makes a four here will be happy enough with their lot.

In last year's Volvo Masters, this hole was the third hardest, averaging 4.37 shots.

Ninth hole 441 yards Par 4

"The Wall"

Again, the drive is of immense importance. There is out-of-bounds down the right, but anyone thinking they can take the soft option by putting their drive down the left will also be in trouble as they will find themselves cut off by trees with no shot to the green. And, because of its length, you cannot lay up. So, the premium is on a good, long, straight drive.

It's a tough hole. The approach shot is to a slightly raised green that runs away front to back, an element of design which I'm not really in favour of. It is also very quick right to left. It's another smallish green, which demands an accurate second shot with little or no room for error.

This was the hardest hole in the 1996 Volvo Masters, averaging 4.43. In last year's tournament, it yielded just 15 birdies in 260 attempts.

12th hole

197 yards Par 3

"The Camelias"

I would describe the green here as resembling a hog's back - and, given its distance from the tee box, it requires an exceptionally hit shot to find the putting surface. Anything hit marginally right will simply roll off the right side, anything marginally left will roll off that side. It is a very long par three that inflicts more than its share of punishment. Put simply, you can't afford to miss the green left or right; and even if you finish up short, to the front, a difficult pitch awaits. This is one of the toughest holes any player will meet anywhere. There is out-of-bounds all the way down the right hand side and the extremely undulating green is surrounded by four large bunkers. I know many players who felt they had the hard work done by finding the green, only to three-putt and walk off with a bogey. I expect to witness plenty of heartache on this hole.

Consistently tough - thoughout the nine-year stint of the Volvo Masters, this hole was regularly rated second toughest on the course.

16th hole

422 yards Par 4

"Very Difficult"

There is always one hole on a course which, in matchplay, has particular significance. This hole, a dogleg right, comes at a potentially vital stage in a match and you can't afford to show any fear off the tee. It is essential to drive up the left hand side, as the fairway slopes right-to-left, and to make sure you get far enough past the dogleg. After that, the onus is on a good iron shot to a smallish green which is very fast back-to-front and left-to-right. It is better to finish short of the flag than past it. However, it is a good matchplay hole and it will exert a lot of influence on the outcome of matches.

What's in a name? The Spaniards christened it Muy Dificil (Very Difficult) for a reason. It is.