Monday 28 December 2015 12:38, UK
2015 has brought more change at the top of the official golf world rankings than any other year since the system was introduced nearly three decades ago.
Rory McIlroy's record-breaking run during the second half of 2014 saw him head in to the New Year with nearly a three point advantage over the chasing pack, with Henrik Stenson's season-ending DP World Tour Championship victory putting him in second spot ahead of former world No 1 Adam Scott.
That lead was soon extended on the Desert Swing, with a runners-up finish in Abu Dhabi followed by victory in Dubai to move McIlroy more than four points in front.
A four-week break did little to change the Northern Irishman's position, although a missed cut at the Honda Classic on his return did see the gap between him and new No 2 Bubba Watson shrink slightly.
Further down the rankings, Jason Day's win at the Farmers Insurance Open had temporarily parachuted him to fourth spot, before Jordan Spieth took the position by adding two second-place finishes to his win at the Valspar Championship.
With Spieth heading to the Masters as the man in form, the then 21-year-old produced a dominant display to become the first wire-to-wire winner at Augusta in nearly 40 years.
Victory in the opening major of the year lifted Spieth to second in the world but some way short of McIlroy, only for Rory to restore his considerable lead by winning the WGC-Cadillac Match Play and the Wells Fargo Championship in a three-week stretch.
After McIlroy posted back-to-back missed cuts at Wentworth and in Ireland, Spieth maintained his strong form with a tied-third finish at the Memorial, giving him confidence ahead of the second major of the year.
A narrow win over Dustin Johnson at the US Open pulled Spieth closer to McIlroy, who wouldn't return to action for nearly two months after rupturing ankle ligaments playing football with friends.
While the majority of players elected to get links course practice at the Scottish Open, Spieth returned to the John Deere Classic and won the event for a second time.
The Texan could have taken top spot if he'd followed that win in Ilinois, the venue of his maiden PGA Tour triumph, with another at the Open Championship, but Spieth ended up one-shot short as Zach Johnson took the title in a play-off.
Although Spieth's near-miss at St Andrews a week later denied him a third straight major victory and the top spot in the rankings, the American was able to end McIlroy's 54-week stint as world No 1 by finishing second to Jason Day at the PGA Championship.
The swing meant Spieth also replaced McIlroy as the second-youngest player to top the world rankings, only bettered by Tiger Woods' rise up the standings during his breakthrough year in 1997.
It wasn't long though before top spot had changed hands again, with McIlroy returning top of the standings despite not even featuring at The Barclays.
Spieth failed to qualify for the weekend at Plainfield CC, while Jason Day's third win in five weeks closed the gap between the trio heading into the PGA Tour's FedExCup play-offs.
All three of them had a chance to end the Deutsche Bank Championship at the top of the rankings, but it was the two-time major winner that reached top spot despite a second early exit in as many weeks.
His missed cut, combined with McIlroy's tied-29th finish after a two-week break, meant Day could haven taken pole position with a victory but only finished tied-12th.
A change in the averages during an empty week on the PGA Tour schedule moved McIlroy less than 0.03 points clear of Spieth in top spot, only for the Northern Irishman to see his seventh stint as world No 1 come to an end at the BMW Championship.
Day built up a convincing lead and continued to extend his advantage on his way to a six-shot win, his fourth victory in six starts, making him only the third Australian to ever reach No 1 in the rankings.
Despite Day going into the season-ending TOUR Championship as the man to beat, Spieth ended the week as world No 1 and top of the money standings after adding another victory to his record-breaking year.
With the averages taking into account performances over a two-year period, Day edged ahead of Spieth in mid-October, only for the numbers to work in the American's favour and put him back top three weeks later - the position he will hold going in to the New Year.
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