The things you need to know about this week’s US PGA Championship

1. Three players have a chance of starting next week as world No.1. Dustin Johnson, the current incumbent, could stay there. However, current No.2 Justin Thomas and No.3 Justin Rose could leapfrog him depending on how results go at Bellerive. Thomas can get there if he wins and DJ finishes worse than a three-way tie for second, or if Thomas finishes second, Johnson does worse than a two-way tie for 18th and Rose does not win. Rose, meanwhile, can climb to the top of the pile for the first time in his career if he wins and Johnson finishes worse than a two-way tie for seventh.