Rory McIlroy is poised to return to the top of the Official World Golf Rankings (OWGR) for the first time since 2015, dethroning Brooks Koepka in a situation described as "interesting and rare".
The Northern Irishman will move above Koepka when the next edition of the rankings go live next week, even though both he and the American will not be playing at the Pebble Beach Pro Am, which begins in California on Thursday.
McIlroy has had seven spells as the world number one, though he has not held the position since losing it to Jason Day in September 2015.
Koepka is in his fourth spell at the summit and has been on top since May, the longest streak since Dustin Johnson's 64-week run came to an end in May 2018.
Jon Rahm had the chance to move into first place at last week's Phoenix Open but his finish of joint-ninth was not enough and the Spaniard will also not be playing at Pebble Beach.
McIlroy will leapfrog Koepka because he is losing points at a slower rate in the OWGR system that calculates ranking positions.
The OWGR described the quirk by saying: "The current OWGR situation with Brooks is interesting and rare".
Points are allocated over a two-year period, with the previous 13 weeks holding the highest weighting.
A spokesman added: "He has had two extended periods of injury during the last two years and both are working against his OWGR currently.
"He didn't play between Week 48 of 2017 and Week 18 of 2018 because of a wrist injury, so every time he plays for the next three months will add one to his divisor.
"Most of his competitors will maintain a more or less constant divisor over that period. This means Brooks needs to win relatively approximately 2.5 per cent more points each time he plays to maintain his average.
"He has not won many points within the last three months, mainly due to not playing because of a knee injury. This means he is losing points because all of is performances are in the period of decay, i.e. older than three months.
"He is losing points at a greater rate than all the other players."
McIlroy, who won the last of his four majors in 2014, finished in a tie for third at the PGA Tour's Farmers Insurance Open last month.
Koepka, meanwhile, has finished outside the top 10 in his two appearances on the European Tour so far in 2020 and concluded last season earlier than his rival as he struggled with a knee injury.