Haven, Wis. – For the third consecutive major, Jason Day holds the lead or a share of it.

The Australian leads the PGA Championship at Whistling Straits by two shots entering Sunday's final round, and at 15 under par he holds the second-best 54-hole score in PGA history.

He is a likeable figure. He played through the U.S. Open despite a bout of vertigo. He sometimes ends interviews by saying, "Cheers!" And he hits his driver so high and far you wonder whether the golf ball will burn up during reentry.

If he were playing in the final pairing with anyone other than Jordan Spieth, he might have Americans cheering for him tomorrow. Instead, he will be the guy trying to keep Spieth from making history, even as Day tries to make his own.

"If he goes out and wins tomorrow from him putting well, then he deserves it," Day said after his 6-under 66. "But I'm going to give him a fight."

Day holds a two-shot lead over Spieth and is three ahead of Branden Grace and Justin Rose.

Sunday, Day will become the player who broke through to win his first major, or another player who couldn't close out a championship.

Which is why he spent part of Saturday night repeating mantras to calm his nerves.

"I've been here before, so I kind of know what to expect," he said. "I haven't won before, so that's something that is possibly a new experience for me tomorrow …

"I just have to stay out of my own way."

The last player to hold the lead after 54 holes in three consecutive majors was Tiger Woods, during his prime.

Day has played in the same group in majors three times. During those rounds, Spieth was 8 under par; Day was 4 under.

"My confidence level is high," Day said. "But I'm just more enjoying being out on the golf course, rather than in previous positions that I've had in major championships.

"I've viewed them as very stressful and kind of hard to go out and play the next day. But I'm enjoying myself so much out there."

Day drove the ball so well on Saturday that, one a 565-yard par 5, he hit the ball pin-high with a driver and a pitching wedge.

Spieth won't be able to match Day's length. Can Day match Spieth's course management, putting, and competitiveness?

"I have to mentally prepare myself that things might go wrong tomorrow, and things might go right," Day said. "But you've got to make sure that you just keep pushing forward. And that's the mindset I need to take into tomorrow."