Cameron Smith's Masters hopes disappeared with a shot into Rae's Creek at the 12th in the final round

Australia's Cameron Smith spent the best part of four days putting himself in position to win The Masters, but it all fell apart with one horror shot in the final round at Augusta National.

The Queenslander came into the Masters as one of the form players after his win in the so-called «fifth major», the Players Championship last month.

Smith went into the final round three shots behind leader and eventual winner Scottie Scheffler, and he was still in contention with seven holes left before disaster struck.

He has spoken of his frustration at the moment it all went wrong. 

The 28-year-old was within three shots of the lead after a birdie on 11, and he turned up at the famous 140-metre par-three 12th and decided to go for it.

The middle hole of the trio of holes known as Amen Corner has proven lethal to players' hopes of winning over the years, making caution a decent option for many.

But instead of heading for the safety of the middle of the green and waiting to try for a possible eagle on the par-five 13th, Smith tried to land the ball on a narrow strip of green near the pin — only to produce a terrible shot.

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His hand came off the club as he realised he'd got it wrong, and the ball landed with a splash in Rae's Creek.

Smith finished the hole with a triple-bogey six, and dropped back to 4-under. His chances of a breakthrough Masters win fell away with it.

«A poor shot on 12, and there's the tournament,» he said.

«It was all fine.

»It was a perfect nine iron, and just a really bad swing. Probably my worst swing of the week at the worst time of the week. I'll learn from it and be stronger from it."