Rory McIlroy has returned to the top of the Official World Golf Rankings this Monday morning, for the first time since 2015.
In those four and a half years, that's gone on for 230 weeks, McIlroy has won nine tournaments, the Ryder Cup and has been named the Player of the Year on the European and PGA tours.
The four-time major winner has leapfrogged Brooks Koepka following last week's action at the AT&T Pro-AM in Pebble Beach.
2019 was a particularly good year for McIlroy, one of the most consistent of his career.
Having not won for exactly a year he took the Player's Championship at Sawgrass in March.
He then enjoyed three more top ten finishes before he won the Canadian Open by seven shots in June, with fellow countryman Shane Lowry second.
McIlroy's recovery from the disappointment in The Open at Royal Portrush, in front of a home crowd, was also notably impressive.
After failing to make the cut at the Major that he was one of the favourites to win he came back to win the PGA Tour's Fed Ex Cup, for the second time.
He played alongside Koepka in that tournament and finished five shots clear of him.
American Koepka has been dismissive of the rivalry between him and the Ulsterman and speaking at the CJ Cup last year he said;
"I'm not looking at anybody behind me. I'm No. 1 in the world.
"I've got open road in front of me ... I'm not looking in the rearview mirror, so I don't see it as a rivalry."
It's the longest gap between spells as the world's best for a single player since the rankings were introduced back in 1986.
McIlroy first reached World Number One by winning the Honda Classic in 2012 and since then no player has held the top spot on more occasions and he's fourth on the all-time list for weeks spent at number one.