Norman won at Royal St George's in 1993 Thurs & Fri tee times

Greg Norman has warned his Open Championship rivals that the Royal St George's course could change beyond all recognition if the weather alters.

The Australian, the last man to win The Open in Sandwich back in 1993, insisted a few practice rounds may not be enough to learn the ropes on the tough seaside links set-up.

And he stressed that the winner may not be an obvious contender like world number one Tiger Woods but someone who has played well at the course in the past.

"If the weather conditions change like they're predicting, it's going to be a totally different golf course on Thursday morning," said the 48-year-old.

Photo gallery: Open practice

"You'll get to know it with the north-east wind and then all of a sudden it's going to change and instead of hitting it 260 yards off the tee into the wind, you're hitting it 350 yards off the tee downwind."

The fairways at times are like playing on the moon Ernie Els

Defending champion Ernie Els agreed, saying: "It's true links golf.

"There's nothing flat on this course, everything bounces away.

"The fairways at times are like playing on the moon and you have to take the rough with the smooth."

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Norman, who fired a closing 64 to beat Nick Faldo a decade ago, added: "It's a shotmaker's course.

"It's quirky because there's so many nuances about how you can approach the game around here.

"You can play it aggressive if you want or as conservative as you like. Some of the shots are semi-blind, some shots you have to trust the distance how far you hit it through the air.

"But then you have to calculate a 60-yard run, and hopefully that run is going to be straight.

"It's a tough course to play mentally."