"I feel like heading into Thursday's round, that I'm not searching to find something, that I have what I'm looking for," he said of the upcoming tournament. "I just have to maintain it and put together mentally a good four solid rounds."
More than a decade has gone by since Mickelson suffered a winless season. This year, he doesn't even have a Top 10 finish on the PGA Tour.
On Sunday at Firestone Country Club, he managed 10 birdies against two bogeys to finish eight under par for the day. That represents his best round of the year.
The PGA Championship is scheduled to tee off Thursday at Valhalla Golf Club in Kentucky.
"All you need is for it to just click one day, and all of a sudden, you're off and running," Mickelson said. "Now, I don't know what will happen next week, but if I play well, if I play well next week, I'll look back to today's round as being the key point."