The 63-year-old two-time champion, who had played in 44 consecutive Masters tournaments, told his friend what all grown-ups tell kids who are about to hit a golf ball. "Keep your head down and focus."

While Spieth welcomed Crenshaw's advice, the 21-year-old admitted his experience at last year's Australian Open - and the infuence of his Melbourne-born coach - was more significant as he held on to his lead in the final round at Augusta.

It was in Sydney that he learnt to win. "I had some struggles towards the top of the leaderboard on Sundays – it was trial and error a couple of times – but at the Australian Open we found the solution against a world-class field," said Spieth.

"It was a special week for me and obviously did a lot for my career. Without it, I may not be here right now. Closing out that tournament meant a lot."

Spieth became the first player to get to 19 under par at the Masters when he birdied the 15th, but a bogey at the last put his final score level with Tiger Woods' record low of 270 from 1997. Woods was also 21.

Geoff Ogilvy remembers the day Spieth came of age at the Australian Golf Club in November last year, shooting an extraordinary 63 in tough conditions on the final day to win by six.

"You can't understand how good a score that was," said Ogilvy. "The Australian's hard with no wind and it was puffing that day. And then Jordan shot eight under par. It was off the map. Beyond comprehension."

Woods also believes Spieth's success that day played a part in his victory at Augusta. "I think Australia probably spurred him on a lot last year, to win down there by a big margin," said Woods.

Spieth confirmed he was planning to return to The Australian this year to defend his title – and his links to Australia don't end there. Victorian Cameron McCormick, who is based in Texas, is his coach.

"I've trusted Cameron since I was, what, 12, turning 13, so eight or nine years. I have complete trust in anything he says. He's my swing coach, putting coach, short-game coach, mental coach, everything," Spieth said.

Spieth said he suffered from nerves, but it didn't show. The biggest challenge he seemed to have was getting his right arm into his new green jacket, which was presented by last year's champion Bubba Watson.

"It was very nerve-racking, I didn't sleep well last night," he said and added he would probably sleep in the green jacket for the next few nights.

Golf is now salivating at the prospect of a long-time rivalry between Spieth and world No.1 Rory McIlroy, who fluffed his chance to win the Masters in 2011 when also 21 and also having a four-shot lead. McIlroy quickly lost control and shot an 80.

This time he finished strong, with a final-round 66 giving him fourth spot. McIlroy is still No. 1, as he was quick to point out after his round. Spieth was his usual modest and impressive self when asked about the Northern Irishman. "He has four majors. That's something I can only dream about. I'll never hit it as far as he does, so I'll have to make up for that somewhere else too. He's an unbelievably nice guy who carries that world No.1 [tag] with class."

Spieth has a tight-knit family and throughout the week he has paid special tribute to his sister Ellie, who has a neurological disorder. "Being Ellie's brother humbles me every day of my life," he said. "I'm sure she was watching and was excited when I won."

Spieth's lead was never less than three all day, and each time playing partner Rose challenged, Spieth responded. They both birdied the first and after Rose holed for birdie on the second and Spieth didn't, the American simply got the shot back on the third. It was that type of day.

Rose, who finished joint second with Phil Mickelson, had a brief chance to pressure Spieth again on the 16th, but his birdie putt slid by and when Spieth holed a tricky two-metre slider for par, the tournament was over.

Rose said he was surprised Spieth had managed so much so young. "It shouldn't be that easy so you take your hat off and marvel at him," said the Englishman.

He has already started adjusting his goals, but is taking baby – or Bubba – steps. "Now I want to be like Bubba and win two Masters," he said.

LEADERBOARD

270: Jordan Spieth (US) 64 66 70 70

274: Justin Rose (ENG) 67 70 67 70, Phil Mickelson (US) 70 68 67 69

276: Rory McIlroy (NIR) 71 71 68 66

277: Hideki Matsuyama (JPN) 71 70 70 66

279: Paul Casey (ENG) 69 68 74 68, Ian Poulter (ENG) 73 72 67 67, Dustin Johnson (US) 70 67 73 69

280: Charley Hoffman (US) 67 68 71 74, Zach Johnson (US) 72 72 68 68, Hunter Mahan (US) 75 70 68 67

282: Rickie Fowler (US) 73 72 70 67, Ryan Moore (US) 74 66 73 69, Kevin Na (US) 74 66 70 72, Bill Haas (US) 69 71 72 70, Kevin Streelman (US) 70 70 70 72

283: Sergio Garcia (ESP) 68 74 71 70, Tiger Woods (US) 73 69 68 73

284: Henrik Stenson (SWE) 73 73 70 68, Louis Oosthuizen (RSA) 72 69 71 72

285: Russell Henley (US) 68 74 72 71

286: Keegan Bradley (US) 71 72 75 68, Patrick Reed (US) 70 72 74 70, Angel Cabrera (ARG) 72 69 73 72, Mark O'Meara (US) 73 68 77 68, Bernd Wiesberger (AUT) 75 70 70 71, Ernie Els (RSA) 67 72 75 72

287: Webb Simpson (US) 69 75 72 71, Morgan Hoffmann (US) 73 72 72 70, Steve Stricker (US) 73 73 73 68, Jonas Blixt (SWE) 72 70 70 75, Jason Day (AUS) 67 74 71 75

288: Jamie Donaldson (WAL) 74 71 76 67, Ryan Palmer (USA) 69 74 74 71, Brooks Koepka (US) 74 71 71 72, Bae Sang-Moon (KOR) 74 71 72 71, Chris Kirk (US) 72 73 72 71

289: Noh Seung-Yul (KOR) 70 74 72 73, Cameron Tringale (US) 71 75 69 74, Charl Schwartzel (RSA) 71 70 73 75, Danny Willett (ENG) 71 71 76 71, Adam Scott (AUS) 72 69 74 74, Bubba Watson (US) 71 71 73 74, Jimmy Walker (US) 73 72 74 70, John Senden (AUS) 71 74 72 72

290: Matt Kuchar (US) 72 74 72 72, Lee Westwood (ENG) 73 73 70 74

291: Geoff Ogilvy (AUS) 74 70 73 74292: Anirban Lahiri (IND) 71 75 74 72, Jason Dufner (US) 74 71 74 73

293: Erik Compton (US) 73 72 74 74

294: Darren Clarke (NIR) 74 71 77 72, Graeme McDowell (NIR) 71 74 76 73

295: Vijay Singh (FIJ) 75 70 79 71297: Thongchai Jaidee (THA) 75 70 80 72