Brooks Koepka is struggling for the first time in defense of his PGA Championship. He saw his lead over Dustin Johnson cut to two shots on the back nine of the final round.

Koepka, who has led almost from the outset, bogeyed the 11th, 12th and 13th holes, with poor driving in windy conditions contributing to his problems.

Meanwhile, his close friend and workout buddy Johnson was remaining steady with the best round of the day. He made birdie on No. 15 for the fourth straight day to pull within two strokes.

Koepka is seeking to become the first player to hold back-to-back titles in two majors at the same time. Johnson has won one major, the 2016 U.S. Open.