Brooks Koepka got the inside track against Justin Thomas in their head-to-head battle this week for world No. 1.
Koepka shot 1-under 71 on Thursday at the CJ Cup, while Thomas shot 1-over 73.
Chez Reavie leads after 18 holes at Nine Bridges in Juju Island, South Korea, following a 4-under 68.
Koepka, currently world No. 3, needs to win this week or finish solo second [without Thomas winning] in order to reach the top spot in the rankings for the first time in his career. Thomas, currently No. 4, must win to reclaim the position he surrendered in June.