By Mark Lamport-Stokes AUGUSTA, Georgia (Reuters) - The ecstasy of Danny Willett's three-shot victory at the Masters on Sunday will forever be linked to the eye-popping agony of Jordan Spieth's stunning collapse on the back nine at Augusta National. Renowned for his mental toughness under pressure and already the winner of two major titles at the tender age of 22, Spieth was seemingly poised for a second successive Green Jacket after storming five strokes clear with nine holes to play. "If you would have told anybody in the golfing world that Jordan Spieth, with the lead, would make seven birdies on Sunday at Augusta and loses, they would have said you're crazy," said former world number one David Duval.
