Golf.com's Jessica Marksbury, Shane O'Donoghue and John Garrity break down the final round of PGA Championship action and discuss what the future holds for 4-time major champion Rory McIlroy.

LOUISVILLE, Ky. — Bubba Watson turned the 2014 Masters into his Sunday stroll. Martin Kaymer lapped the field at June's U.S. Open. Despite his big lead getting trimmed by day's end, Rory McIlroy was never seriously threatened in the final round as he walked in the park at the British Open.

The PGA Championship made up for a major championship season devoid of drama with one waterlogged and wonderful Sunday.

That it ended with McIlroy making history, and rushing to beat darkness after a rain delay of 1 hour, 51 minutes, made it all the more memorable. Not that his shot-making didn't already do so.

Posting his third straight victory overall, McIlroy became the first PGA Tour player since Padraig Harrington in 2008 to win consecutive majors. And, at 25, McIlroy became the third-youngest in the Masters era (post-1934) to win his fourth major overall behind the terrific twosome of Jack Nicklaus and Tiger Woods.

McIlroy shot a 68 to finish 16 under for the tournament, one stroke better than runner-up Phil Mickelson and two better than Rickie Fowler and Henrik Stenson. The Northern Irishman needs only the Masters for a career Grand Slam.

The afternoon tee times were pushed back after a downpour soaked Valhalla with an inch of rain in less than an hour and workers scrambled to clear the course of casual water.

This delay eventually created an almost unprecedented scene on the 72nd hole. McIlroy and Bernd Wiesberger received permission from officials to hit their tee and second shots on the par-5 18th as the next-to-last group of Mickelson and Fowler walked to their shots so that the round could be completed.

This almost-staggered foursome gave McIlroy a bird's-eye view of Mickelson almost chipping in for an eagle that would've forced McIlroy to finish with birdie. After Mickelson tapped in for birdie, McIlroy, whose drive almost found water, two-putted for an adventurous par in near-darkness after blasting out of a bunker.

"It's been just incredible," McIlroy said of his run. "I didn't think in my wildest dreams I'd have a summer like this. I've played the best golf of my life. I think I showed a lot of guts."

So steady all week, McIlroy bogeyed two of his first six holes to fall behind by as many as three shots. He didn't card his first birdie until executing a delicate up-and-down on the par-5 seventh.

Then came a shot for the ages.

Blasting a 3-wood from 281 yards on the par-5 10th, McIlroy appeared to catch the shot slightly on the heel of his club. But his low runner ran alongside the left side of the hole and to within 7 feet. He drained the eagle putt.

"The ball flight was probably around 30 feet lower than I intended and the line of the shot was 15 yards left than I intended," McIlroy said. "So I was lucky."

McIlroy added a fist pump when he birdied the par-4 13th to tie the leaders at 15 under and tacked on a huge birdie out of a fairway bunker on No. 17 after the others stumbled.

Mickelson joined the leaders three times with birdies and stayed there with a 27-foot par putt on the par-4 12th. But after almost holing out a birdie chip on the difficult, par-4 16th, Mickelson missed the putt coming back for his first bogey in 21 holes.

"I'm disappointed," Mickelson said. "Had I been able to finish those last five or six holes strong, it could have totally flipped the way I look at this year. Now I've got some regrouping to do these next three or four months and some glaring areas in my game I have to work on."

Fowler joined Nicklaus and Woods — who each did so twice — as the only golfers in the modern era to post top-five finishes in each of the season's majors but the first to do so without a victory.

Fowler took the outright lead three separate times, including a chip-in on the par-4 fifth and a 25-foot birdie on the par-5 10th. But his bogey after pushing his tee shot on the par-3 14th proved costly, dropping him out of the lead for good.

"This is the one that hurts the most," Fowler said.

At the end, McIlroy had to catch the lid of the Wanamaker Trophy as it got presented to him, a fitting end to a dramatic day.

kcjohnson@tribune.com

Twitter @kcjhoop