LOUISVILLE, Ky. -- It's certainly not a case of Rory McIlroy being unable to win his third straight tournament and second major championship in a row Sunday.
The world's No. 1-ranked golfer owns a 1-stroke lead going into the final round of the PGA Championship at Valhalla.
But the challenge of closing out another tournament is a bit different this time.
"The leaderboard is the most jam-packed it's been since the final round of the Masters," said Rickie Fowler, who is 2 shots behind McIlroy. "It's there for the taking, for sure."
But if it's not McIlroy taking it, then who?
He will play in the final twosome with Austria's Bernd Wiesberger, the surprise of Round 3 with his 6-under-par 65. He is 1 shot behind McIlroy's 14-under 200 total for the first 54 holes.
Wiesberger, though, is playing in the last group of a major for the first time. Before this week, the only time he made a cut in a major was in 2013, when he tied for 64th in the British Open. Wiesberger will feel the pressure -- just like he has in the past.
"I've never played well in the majors," he said. "I've played well in other bigger events in Europe and won a couple, but that's not the same. (A major) is on a different level.
Phil Mickelson, Fowler's final-round playing partner, is the most experienced of McIlroy's challengers. He has wins in the Masters, British Open and PGA but has had a subpar season. Saturday's 67 followed a 62 in the last round of the Bridgestone Invitational last week.
Those two encouraging rounds might have put Mickelson back on the right track. He is 3 behind the leader.
"It's so fun for me to be back in the thick of it, to have a chance, to be in contention heading into Sunday," he said. "I don't have to get up a six o'clock in the morning to tee off. That's a nice change."
Eighteen players are within 6 shots of the lead. Among the others are Australian Jason Day (tied with Mickelson), Louis Oosthuizen, Henrik Stenson, Steve Stricker and Hunter Mahan. They're all established stars, and Mahan's 65 matched Wiesberger for the low round Saturday.
But the best bet to slow down McIlroy is Fowler. He has been the best player in the first three majors, though he didn't win any of them. He tied for fifth in the Masters, which was won by Bubba Watson, and was joint second at both the U.S. Open, which was taken by Martin Kaymer, and the British, which went to McIlroy.
Fowler loves the pairing with Mickelson in the next-to-the-last group.
"I'm in a great position for tomorrow," Fowler said. "Phil and I are going to have some fun. If we get off to good starts we can feed off each other."
The near-misses in the year's previous majors also bode well for Fowler's chances. He feels his time will come -- maybe Sunday.
"I expect to feel more comfortable than I did in the last two majors," he said. "The past three majors were building blocks. Now I've got to go out and get one."
Fowler's game was solid Saturday -- a bogey-free 67 -- but he didn't get all he could out of it.
"I was swinging very well," he said. "I had a lot of good looks for birdies, especially on the back nine. I made great swings, but nothing went in. I'd just like that the putts that didn't go in today can go in tomorrow."
As for McIlroy, who held 1-stroke lead after both 36 and 54 holes, Fowler knows he will be tough to beat. "He's playing with a lot of confidence, and he's not going to back up," Fowler said. "Being patient is key. I've got to go shot for shot."
McIlroy stayed patient Saturday. He 1-putted nine of the last 12 greens, while Wiesberger, Fowler and Mickelson were making runs at him. At one point, five players (including Ryan Palmer) were tied with McIlroy for the lead.
"I feel like I'm in the best position I can be going into tomorrow," McIlroy said. "I would rather be the guy that's being chased and have that shot advantage than not.
"It's going to be a shootout. The conditions are soft. Guys are going to make birdies, and you know you're going to have to make birdies as well if you're going to win."