Justin Rose described himself "shell-shocked" by his third round 81 in the Masters.

From two ahead Rose crashed nine behind after he bogeyed nine of the 18 holes at Augusta National.

"Whether you believe me or not I felt in a great frame of mind going out there," said the 23-year-old from Hampshire, who had had just two bogeys in his first 36 holes.

"I hit the ball beautifully on the range. I just got off to a bad, bad start and every little minor mistake got punished.

"That is obviously what Augusta is all about. It bit back in a large way.

"I tried my best all day and it was just frustrating. I just tried to grind it out, but hard as I tried I could not turn it around. I tried on every single shot.

"It was tough. My good putts didn't go in, my good shots didn't get rewarded. Every break seemed to go against me. Yesterday it would have gone my way.

"I got a beautiful ovation at the last. That was a nice touch. No matter what happened today it was going to be a great learning experience. At the age of 23 it's not the end of the world.

"It hurts because I was thinking I was playing well enough to win, so that is a shame."

English hopes turned to Paul Casey instead, a 68 taking the 26-year-old into third place on four under par while Rose toppled to 20th spot.

Americans Phil Mickelson and Chris DiMarco lead by two from Casey, with 46-year-old Ryder Cup captain Bernhard Langer now fourth following a 69.

He insists he will not give up the captaincy should he win for a third time on Sunday. It would make him the oldest-ever winner of the Masters.

Swede Fredrik Jacobson, like Casey making his debut in the tournament, is eighth and Padraig Harrington ninth. They shot 67 and 68 respectively.