The world No. 1 says he is almost back to the level he was at before injuring his back on the eve of the US Masters. Then, the American won the Genesis Open in February before claiming two World Golf Championships titles in March - Mexico and Matchplay - to top the rankings.
The 33-year-old's long drives should keep him in the hunt despite expected wet conditions.
He won last week's World Golf Championships-Bridgestone Invitational to serve notice that he has the game for a Major triumph.
Victory would make him the first Japanese man - and only the second Asian man after South Korean Y.E. Yang (2009 PGA Championship) - to win a Major.
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The 25-year-old Matsuyama was joint-second behind Brooks Koepka at the US Open in June.
The 39-year-old enjoyed his best Major finish with a runner-up effort behind Jordan Spieth at The Open Championship last month.
The American, who also shared fourth at the Masters, has nine top 10s in Majors without a victory.
Rory McIlroy (2012 and 2014) is the only PGA Championship winner since 2008 who is not a first-time Major winner.