Jordan Spieth
Spieth claimed the first of what is expected several major championships. Getty Images

Jordan Spieth held off a final day charge from Justin Rose and Phil Mickelson to clinch his maiden major title at the Masters with a record-equalling score of 18-under par at Augusta.

The 21-year-old struck a fourth round 70 to hold off the challenge of Rose and Mickelson, who finished tied for second on 14-under, in a performance for the ages as he led from start to finish at the opening major of 2015.

World No.1 Rory McIlroy was a further three shots back in fourth on 12-under with Japan's Hideki Matsuyma alone in fifth on 11-under after a final day 66.

English duo Paul Casey and Ian Poulter were tied for sixth on nine-under along Dustin Johnson and Charley Hoffman but none of the quartet figured in the pulsating final day in Georgia.

Spieth's heroics saw him surpass Tiger Woods as the joint-highest scoring victor in Masters history and the first player to lead from the opening round to clinch the green jacket since 1976.

After shooting the record lowest round after 36 and 54 holes earlier in the week, Spieth, who doesn't 22 until July, becomes the second youngster player to win the title 18 years on from Woods' win in 1997.

"It was very nerve racking today I thought today might be easier than yesterday but it wasn't," the Texan said. "I didn't sleep well last night, I saw a putt go by on the first hole and we were off. With two major champions behind I couldn't let up.

"It was the most incredible week or my life. This is as great as it gets in our sport. It is a dream come true for me. I didn't break 70 last year but to shoot low rounds and see putts go in was remarkable.

"I saw my family and friends and definitely knew it was going to be a done deal. It still hasn't kicked in and I am sure it will settle in a little later. I am excited to come back and opportunity ahead to be the reigning Masters champions."

Leaderboard: -18: Spieth, -14: Rose, Mickelson, -12: McIlroy, -11: Matsuyama, -9: Casey, Poulter, D. Johnson, -8: Mahan, Z. Johnson, Hoffman