Rory McIlroy ended the most memorable season of his young career on a muted note when he closed with a one over 72 to finish 15 shots behind a sensational Jordan Spieth in the Emirates Australian Open.

Six shots off the lead overnight after a triple-double horror run at the ninth and 10th in a third round 76, McIlroy had to settle for a cheque for $13,867 as he tied for 15th on two over par.

Spieth produced one of the greatest final round performances in the history of the event, carding an eight under par 63 — the lowest round of the day by four shots — to win by six shots from Rod Pampling on 13 under par.

“That was definitely the best round I’ve ever played,” Spieth said on a day that saw Pampling, Brett Rumford and Greg Chalmers qualify for next July's Open Championship at St Andrews. “At the start I didn’t think such a round was out there, but the putts kept going in. It was an awesome experience.”

Even McIlroy expressed his admiration, tweeting: "You could give me another 100 rounds today at The Australian and I wouldn't sniff 63.... Well done @JordanSpieth."

It says it all about McIlroy's final round that he only made his second birdie of the day at the par-five 18th. But he can still reflect on a monumental 2014 season that has brought him two major wins, the Race to Dubai, the PGA Tour's Player of the Year gong and the small matter of €10,767,472 in prize money (including bonuses but not appearance money).

“It was tough, I was going out there trying to get something going but with the pin positions and the wind it was just very hard to get the ball close to the hole," McIlroy said. 

"Anything under par today would have been a good score. I just couldn’t get anything going and I hit a few loose shots again. It just wasn’t meant to be this year.”

McIlroy had no regrets about trying to hit out of the fescue on the ninth on Saturday, moving his ball just a few inches as he got tangled in webbing.

“Not at all. It’s fine. I was trying to play the shot I wanted to play and I just hit a bad shot. I played nine in level par this week – three birdies and a triple,” he said.

"I’m not going to let what happened this week ruin the best year I’ve had."

McIlroy can reflect on an incredible season that brought him his third and fourth majors wins in The Open and the US PGA as well as victories in the BMW PGA at Wentworth, the WGC-Bridgestone Invitational and another five runner-up finishes.

He finished outside the top 10 just seven times in his 24 starts with his only missed cut of the year coming in the Irish Open at Fota Island.

As for the Australian Open, Spieth won in such impressive fashion that golfer writer and former tour player Mike Clayton was reaching for superlatives in his report for the official tournament website:

There have been many great rounds played over the years at the Australian Open. Gary Player’s twice shot 62 in the 1965 Open at Kooyonga but the championship had been moved at short notice from a drought stricken Royal Adelaide and was hardly arranged to test the game’s superstars, Player and Jack Nicklaus.

Five years later at Kingston Heath Player announced after an opening 71 he had no chance to win because he was afflicted with a hook only the unsympathetic and unresponsive Ben Hogan could cure.

He went out the next day and shot an extraordinary 65 prompting the great Peter Thomson, a winner of three Open’s himself, to accuse the South African of ‘laughable emotionalism’.

Player won seven opens, one more than Nicklaus but this week it was Jordan Spieth winning his first with a final round score almost beyond comprehension.

The Australian is the most difficult championship course in the country. The greens are small; they are surrounded by bunkers difficult to play from and defended by steep banks of short grass feeding the ball away from the flags.

Spieth was out in the final group with Rod Pampling and Greg Chalmers, ten minutes behind the obvious choice of winner Adam Scott. Scott instead blighted his score and his chance by making a seven at the par five, 5th hole and in the end a par round was his return. It wasn’t a bad round but it was never going to put any pressure on Spieth.

The American relentlessly hit fairways and greens, birdied the 3rd, followed it up with three birdies in a row from the 5thand then finished up his 63 with four birdies over the final five hole stretch back to the clubhouse.

Whilst the birdies were the brilliant part of the score it would not be unreasonable to argue it was the run of six pars from the 8th, which cemented his win. The holes either side of the turn are the heart of the golf course and where so many had made mistakes during the championship.

Player’s low rounds were played early in the championship but Spieth earns extra points for doing his record score on Sunday when the pressure of a long week culminates. ‘I never left a shot out there’ was the greatest compliment he could play his round and rare are the days when a professional golfer can look back on a round and admit he couldn’t have scored any less.

Probably he is the brightest of the very young American players and it is more than heartening he seems to understand the importance of developing his game outside of America. Players can make fortunes without ever owning a passport by playing the one-dimensional courses found on the PGA Tour but to be judged a truly great golfer one needs to venture beyond the shores of the United States and both test and develop a game in unfamiliar conditions. Spieth played well in Japan last week and whilst The Australian is hardly a typical or traditional Australian golf course Spieth’s win will hopefully see him return, as Nicklaus and Player did, many times to our shores.

No matter what he does on his return visits he will never play a finer round than he did this Sunday in Sydney. In the hundred and ten year history of the championship no man has ever played a better round.

McIlroy's focus now turns to his legal action against Horizon Sports Management, scheduled to run for six to eight weeks from February 3, and his bid for the final leg of the career grand slam at Augusta National in early April.

The discovery process in the legal case will hit the courts again from December 9-10 with Horizon seeking further documentation from McIlroy's father Gerry; the CEO of Rory McIlroy Inc, Donal Casey; and Sean O'Flaherty.

Spieth came close to winning the Masters this year, losing a final round battle with eventual winner Bubba Watson.

On the evidence of his performance at The Australian Golf Club, he's a rival McIlroy will fear.

"I didn't realise Gary Player won it seven times and Jack (Nicklaus) won it six, plus the more recent names of Adam and Rory," Spieth said of the names on the Stonehaven Trophy. "Hall-of-famers, that's what I think of when I see this trophy and you don't see that often on a trophy. 

"It's really cool that my name will go on here and I'll get to keep this trophy ... maybe not this one, but a replica!''

Leading final round scores (Australian unless stated) Par 71

271 - Jordan Spieth (USA) 67 72 69 63

277 - Rod Pampling 73 67 69 68

278 - Brett Rumford 70 69 69 70

279 - Greg Chalmers 71 66 71 71

280 - Adam Scott 74 66 69 71

281 - Jake Higginbottom 71 69 72 69

283 - Robert Allenby 71 69 73 70, Ryan Fox (NZL) 72 72 69 70

284 - Daniel Nisbet 74 72 67 71

285 - Nathan Holman 73 72 73 67, Kang Sung-Hoon (KOR) 73 70 72 70, Aaron Townsend 73 70 71 71, Joshua Younger 71 72 70 72, Aron Price 68 75 69 73

286 - Stephen Dartnall 72 71 74 69, Stephen Allan 75 71 70 70, Steven Bowditch 70 74 71 71, Rory McIlroy (NIR) 69 69 76 72, Richard Green 69 71 74 72, Boo Weekley (USA) 72 71 71 72, Alistair Presnell 74 72 68 72, David Bransdon 72 70 71 73