By Rob Hodgetts BBC Sport at Royal Troon

The 11th - a sea of gorse and out-of-bounds all down the right

"You've got to have built your score by the time you get to the 11th."

That's the maxim the players will have to adhere to if they want to be challenging for the 133rd Open title on Sunday afternoon.

It is also the consensus of the marshals who have watched every shot at the treacherous 490-yard par-four, consistently the hardest hole at Royal Troon.

Named after the railway that marks the out-of-bounds all the way down the right, the tee shot is played blind over a sea of gorse, using the distant redbrick Marine Hotel as a guide.

Ken Brown's guide to the 11th

"It's just an amazing tee shot," said marshal David Semple, of Glasgow Golf Club.

"It's such a narrow chute they have to aim down."

The carry to the front of the fairway is 210 yards, while those straying on a more tigerish line further right will have to fly the ball at least 275 yards to avoid more dense rough.

BACK NINE SCORING STATS 10th - par 4 - Three-round av. 4.296 - ranked 2nd hardest 11th - par 4 - 4.421 - 1 12th - par 4 - 4.291 - 3 13th - par 4 - 4.143 - 9 14th - par 3 - 3.122 - 10 15th - par 4 - 4.268 - 4 16th - par 5 - 4.743 - 18 17th - par 3 - 3.218 - 6 18th - par 4 - 4.203 - 7

Any straight drives overcooked will run into gorse on the left, while a further consideration is the prevailing wind which blows from the north-west, onto the players' left shoulder, though this week it has been more out of the west.

"For a right-hander, any cut on the ball and you've had it," said marshal Hugh Elder, also of Glasgow Golf Club.

The 11th comes at the heart of Royal Troon's own equivalent to Augusta's Amen Corner.

Following the tricky enough Postage Stamp eighth, the treacherous stretch begins at the ninth - with a green guarded by deep valleys - and the 10th - another blind drive - while the 12th continues the agony.

"You need to be conserving what score you've got in this little patch," said Elder.

FRONT NINE SCORING STATS 1st - par 4 - Three-round av. 4.081 - ranked 12th hardest 2nd - par 4 - 4.026 - 14 3rd - par 4 - 4.106 - 11 4th - par 5 - 4.766 - 17 5th - par 3 - 3.145 - 8 6th - par 5 - 4.992 - 15 7th - par 5 - 3.990 - 16 8th - par 3 - 3.049 - 13 9th - par 4 - 4.229 - 5

In fact, the back nine at Troon contains six of the seven hardest holes on the course, with just the 542-yard par-five 16th - the easiest hole on the track - offering an island of tranquility in an ocean of chaos.

The par-four 15th, the fourth hardest hole, is no picnic, while the short 17th, long for a par three at 222 yards, lurks near the end of the round ready to catch anyone who thinks the hard work is behind them.

Ken Brown's guide to the 17th

A real wolf in sheep's clothing, it's a long iron aimed short and right of the left bunker to run up and onto the green.

But the putting surface is lightning quick and the prevailing wind from front left plays havoc off the tee.

"It's a long old smack and the green is like glass," said marshal Alan Clayton, of Troon Portland Golf Club.

"If you walk off with a three you're well pleased."

Which just leaves the 18th, and if you are still in with a chance on Sunday afternoon, the heart will be pounding as you funnel down between the two massive grandstands ready to face your destiny.

For most, though, any remaining hopes and dreams will have been abandoned just after the turn.