A new format was introduced in 2015. Previously, the Championship was a single elimination match play event. Beginning in 2015, the championship started with pool play, with 16 groups of four players playing round-robin matches, on Wednesday through Friday. There are no halved matches in pool play with extra holes played to determine the winner. The top 16 seeded players were allocated to the 16 groups, one in each group. The remaining 48 players were placed into three pools. Each group had one playerrandomly selected from each pool to complete the group. The winners of each group advanced to a single-elimination bracket on the weekend, with the round of 16 and quarterfinals on Saturday, and the semi-finals, finals, and consolation match on Sunday. If two players are tied at the top of the group, the result of their head-to-head match determines the group winner. If three players are tied, the winner is determined by a sudden-death playoff.
Players were divided into 16 groups of four players and played round-robin matches on Wednesday to Friday.
Round 1 – April 29
Round 2 – April 30
Round 3 – May 1
Notes: Round 1 Of the 32 matches played, 14 were "upsets" with the lower seeded player beating the higher seeded player. These included #3 Henrik Stenson, #6 Justin Rose, #7 Jason Day, and #9 Adam Scott. Notes: Round 2 Of the 32 matches played, 16 were upsets. These included #5 Jim Furyk, #7 Day, #8 Dustin Johnson, #9 Scott, and #10 Sergio García. Two players, #13 Rickie Fowler and #60 John Senden, were guaranteed to advance. Notes: Round 3 Of the 32 matches played, 18 were upsets. These included #2 Jordan Spieth, #3 Stenson, #4 Bubba Watson, #7 Day, #9 Scott, and #10 García. Day, Scott and Jimmy Walker were the only top seeds to lose all three matches. Only five of the top seeds advanced: #1 Rory McIlroy, #5 Furyk, #12 J. B. Holmes, #13 Fowler, and #16 Hideki Matsuyama. 12 of the 16 group winners advanced with perfect 3–0 records. Three groups winners advanced based on head-to-head tie-breaker and one group went to a three-way sudden-death playoff. Branden Grace defeated Zach Johnson and Charley Hoffman on the third extra hole in group 7. In Group 11, all six matches of the three rounds were upsets. A total of 18 of the 96 matches went extra holes, causing some to suggest altering the format next year to include halved matches.
Final 16 bracket
Players by pool: A=5, B=3, C=4, D=4 The match between Rory McIlroy and Paul Casey was completed on May 3 having been all square after 21 holes when it became too dark to continue.
