Any of the three could leave the Deutsche Bank Championship on Monday with the No. 1 ranking, according to the new Official World Golf Ranking projections released Saturday.
Day has his first opportunity to get to No. 1 this week. He will get there if he wins and McIlroy finishes worse than solo second and Spieth finishes worse than a two-way tie for second.
Spieth will return to No. 1 if he ties or finishes ahead of McIlroy and Day doesn’t win.
McIlroy is assured he will remain No. 1 with a top-three finish as long as Day doesn’t win. The computations for McIlroy keeping the No. 1 ranking are complicated without Day winning. McIlroy can stay atop the rankings with a top 10 finish depending on what Spieth does. For example, if McIlroy finishes solo 10th and Spieth finishes worse than 58th, McIlroy stays No. 1.
How complicated are the scenarios? Spieth can miss the cut and still move over McIlroy to take back the No. 1 ranking. If Day doesn’t win and McIlroy and Spieth both miss the cut, Spieth goes to No. 1.