With the PGA Championship a little over a week away from teeing off, the AT&T Byron Nelson was set to serve as a tune up for some of the world's best golfers, such as Brooks Koepka. Unfortunately, Koepka's tune-up wasn't meant to be. The four-time major winner made a cryptic decision ahead of the PGA Championship at Southern Hills, as reported by the Golf Channel.

Koepka withdrew from the AT&T Byron Nelson early Wednesday morning, with no reason given. He was replaced in the field by Satoshi Kodaira.

Koepka has withdrawn from the AT&T Byron Nelson and was replaced by Satoshi Kodaira. No reason was given for the Tour star's shocking announcement.

Koepka has dealt with injuries recently, including surgery to repair a dislocated kneecap a year ago. Regardless of the reason, his abrupt withdrawal from the field at the AT&T Byron Nelson certainly puts his participation at Southern Hills in jeopardy.

Koepka hasn't participated in a tournament since the Masters in April, so this was an important tune-up for him. A winner of the PGA Championship twice in his career, Koepka has missed the cut in six of his 13 tour starts this season.

Noe, it appears he'll have an uphill battle towards getting back in the winner's circle at the PGA Championship.