Despite not playing this week, Rose will retake the top spot from Koepka for the third time since November.
Brooks Koepka and Justin Rose just keep playing hot potato with the world No. 1 ranking.
Koepka needed to finish in a two-way tie for eigth or better at this week's Sentry Tournament of Champions to keep the top spot, but a first-round 76 put him behind the 8-ball and an eventual four-day total of four under will see him finish well outside the top 10. That means Rose will take the top spot from Koepka on Monday, the third time that exact scenario has played out since November.
It's the second straight year that Koepka struggled in the event on Maui. In 2018, as he was dealing with a wrist injury that would eventually cause a multi-month absence, his four-day total of 13 over was six shots worse than anyone else in the field.
Rose, who was one of two top-10 players to not play at Kapalua, became world No. 1 for the first time after the BMW Championship in September. The Englishman finished in the top 10 in 15 of his 23 worldwide starts in 2018, including wins at the Fort Worth Invitational and the European Tour's Turkish Airlines Open.
Koepka won both the U.S. Open and PGA Championship last year, but it was his win at October's CJ Cup that saw him reach world No. 1 for the first time. He was named PGA Tour Player of the Year for the 2017–18 season.
This marks the 10th time that the top ranking has changed hands since May—Justin Thomas and Dustin Johnson have also both spent time at No. 1 since then.