The Northern Irishman comes into the final major of the year in fine form, winning his last two tournaments - including The Open Championship at Hoylake last month.
Prior to that win on Merseyside, McIlroy clinched the BMW PGA Championship, while he picked up the WGC-Bridgestone Invitational last weekend.
Following his two-stroke victory at Firestone, McIlroy has rarely been in better shape as he targets a fourth career major title, and second US PGA Crown after his success at Kiawah Island in 2012.
McIlroy is eager to maintain momentum in Kentucky, and sees his challenge further boosted by the back injury suffered by Tiger Woods - an issue that will likely prevent the American from attempting to win his fifth US PGA title.
"These tournaments back to back give you less time to think... and I'll try and play the same golf I have been this week," he said on Tuesday.
"I gave myself yesterday off, which I felt I needed. It is emotionally fatiguing playing tournaments, but not physically.
"Historically this has been my best major and I am looking forward to this week."
McIlroy's impressive form has taken him back to number one in the world rankings - replacing Australian Adam Scott at the summit.
Scott finished eight strokes off the lead at Firestone, with his best US PGA Championship showing coming eight years ago when he tied for third.
However, while admitting McIlroy is the best player on the planet at present, Scott feels he can challenge for a second career major at Valhalla.
"The right guy is number one at the moment," he said.
"He's played the best golf over the past few months. He's won three big tournaments this summer and I've won one event.
"I hope I can win this week and maybe go back to number one."
Scott would return to top spot with victory this week, while Sergio Garcia could also start next week at number one if he can make the final step from nearly man to major winner.
The Spaniard was runner-up to McIlroy at both Hoylake and Firestone, while he has finished tied-second or second in four majors in the past.
In terms of American hopefuls, five-time major champion Phil Mickelson can secure a place in the United States' Ryder Cup team with a solid showing, while Bubba Watson, Jim Furyk, Jimmy Walker, Rickie Fowler, Matt Kuchar and Jordan Spieth can all focus on the task in hand with their spots at Gleneagles already assured.
On the European side, the likes of Luke Donald and Stephen Gallacher will hope to make the most of their last chance to gain points.