The 38-year-old golfer came away from a practice round in the sweltering heat of Atlanta brimming with confidence, reporting: "I'm hitting it a long way and straight. My distance is very good, my accuracy is pretty good, my short game feels good and I'm starting to feel good on the greens."
Westwood starts his first round at 6.55pm UK time in the company of American Matt Kuchar and Jason Day of Australia. But the biggest gallery is likely to follow the group comprising Tiger Woods, United States Ryder Cup captain Davis Love, and Ireland's Padraig Harrington.
Woods, a four-time US PGA winner, has tumbled to 30th in the rankings but Open champion Clarke said: "If Tiger plays the golf he can, I have no doubt he can be in contention."