The American won the Genesis Open to claim the honour
Dustin Johnson has become the 21st player to top golf's world rankings, after winning the Genesis Open on Sunday night.
The US Open champion won at Riviera GC by five strokes from Thomas Pieters and Scott Brown, to overtake Jason Day at the top of the rankings.
Johnson won the tournament after completing 36 holes on the final day in the weather-effected event. A bogey-free third round of 64, followed by a level-par final round of 71 was enough for Johnson to join the elite club.
The 32-year-old missed the opportunity to break the low score at Riviera of -20. He was on that score after seven holes of his Friday round, but failed to birdie any other holes in his final round.
Johnson started the week at third in the rankings, and revealed after the match, he was unsure of the complex mechanics of the rankings. "I don’t really understand it," Johnson said, "but I can read the 1, 2, 3. I guess that’s all that matters."
The win meant that Johnson was won at least one tournament for at least ten seasons in a row. Only Arnold Palmer, Jack Nicklaus and Tiger Woods have achieved that feat.
Padraig Harrington struggled in the final round, shooting a 72, to drop back to a tie for 39th place. Graeme McDowell finished 30 spots further back on +3.