Jason Day is the new world No. 1 in the Official World Golf Ranking.
Day will officially assume the top spot in the ranking at the conclusion of the WGC-Dell Match Play on Sunday. However, by advancing to the semifinal round on Sunday morning at Austin Country Club, the Aussie will pass Jordan Spieth, who has been No. 1 in the world since winning the FedEx Cup at the Tour Championship in September.
In the semifinal round, Day will square off against world No. 3 Rory McIlroy, who will hold that position regardless of the Sunday results. Were Day to win against McIlroy, he'll play in the championship match against the winner of the Louis Oosthuizen vs. Rafael Cabrera-Bello tussle.
Spieth will likely have an opportunity to once again assume the top spot in the ranking. He's playing in next week's Shell Houston Open, a tournament where he finished a playoff loser last year to J.B. Holmes.