PGA Championship 2013: Who Are This Year's Top Sleepers Heading into Oak Hill?

The 2013 PGA Championship begins Thursday at Oak Hill Country Club in Rochester, N.Y. to wrap up golf's major season.

While Tiger Woods figures to be the prohibitive favorite after his dominant win at the WGC-Bridgestone Invitational, a number of other players, who may not be as prominently discussed in the headlines, are worth keeping an eye on.

Jason Dufner and eventual winner Keegan Bradley weren't exactly household names before doing battle in a playoff at the 2011 PGA, but both went on to play on the USA Ryder Cup team.

Although Rory McIlroy trounced the field last year by a record eight strokes at Kiawah Island, the runner-up was little-known European Tour veteran David Lynn. If not for McIlroy's dominance, the Englishman could have been one of the more unlikely champions in major history.

Speaking of which, the last time Oak Hill hosted this championship was 2003, and Shaun Micheel won thanks to a historic approach from the 18th fairway, staving off Chad Campbell by two shots.

Oak Hill played more like a U.S. Open or difficult British Open venue that year, as only three players broke par by the end of 72 holes.

The lesson here: Anything can happen on any given week in golf—especially at the PGA Championship.

Let's take a look at the biggest sleepers who could shock the sporting world and possibly raise the Wanamaker Trophy this coming Sunday.

Note: Statistics and information are courtesy of PGATour.com. Tournament history was obtained via the Official World Golf Ranking. The complete PGA Championship field is available at PGA.com.

Kyle Stanley

This would be quite a story considering the roller coaster Kyle Stanley has been riding over the past two years or so.

Near the beginning of 2012, he had a great chance at his first PGA Tour victory with a 54-hole lead of six strokes at the Farmers Insurance Open. Unfortunately, Stanley blew it by making a triple bogey at the par-five 18th and lost in a playoff to Brandt Snedeker.

Many young players would be too devastated to even golf for a few weeks, much less tee it up at the next tour stop.

Instead of dwelling on his loss, Stanley promptly showed up at the Waste Management Phoenix Open and mounted a rally of his own that Sunday, firing a six-under 65 at TPC Scottsdale to nip Ben Crane by one shot. Stanley started the day eight shots behind overnight leader Spencer Levin.

However, another top-10 finish didn't come until this year, when Stanley finished third at the Zurich Classic of New Orleans in late April.

Stanley immediately followed with a joint sixth-place showing at the Wells Fargo Championship and later came in third at the Memorial Tournament.

A nightmarish weekend at the U.S. Open and four missed cuts in a row later, the 25-year-old American was back to the drawing board.

Something clicked at the British Open, because he followed a horrendous opening-round 85 with a two-under 69 and came in a tie for 12th in the RBC Canadian Open at Glen Abbey.

With magnificent length and a knack for hitting a ton of greens in regulation, it all falls on Stanley's putter to get hot at the right time. At Oak Hill, after all his trials and tribulations, it just may be time for him to officially arrive.

Richard Sterne

Few would guess Richard Sterne would be ranked ahead of players like Rickie Fowler, Billy Horschel, Angel Cabrera or 2010 PGA champion and former world No. 1 Martin Kaymer.

That's the case, though. He's missed just one cut all season and is becoming one of the steadier and more consistent players on the planet.

If Oak Hill plays nearly as difficult as it did a decade ago, the course will suit Sterne well based on his performance at the British Open. Over the final 36 holes, he played the extremely tough Muirfield Golf Links in one under par and finished tied for 21st.

Not long before that, Sterne was runner-up to Graeme McDowell in the European Tour's Alstom Open de France. The South African also won his native Joburg Open in his second start of 2013 after placing second in the Omega Dubai Desert Classic.

Sterne can go low when he's on, and he wrapped up another solid week at the Bridgestone Invitational inside the top 10. To date in Europe, he has his lowest putting average since 2006 and has hit 63.75 percent of fairways and over 70 percent of greens in regulation this season.

That type of precision from tee to green will serve him well at the PGA Championship and may make him as a surprise name in contention.

Paul Casey

The talent has always been there for Paul Casey, but various problems have led to a career that has never quite reached expectations.

With his natural touch on short game shots and brute strength thanks to a dedication to physical fitness, all the tools for success are there.

The Guardian's Ewan Murray recently did a story on Casey and the troubles he's endured in the mental aspect of the game, which is truly what separates the best from the rest.

In the piece, Casey said, "When you are playing good golf, you have no idea how anybody can play bad golf. When you are playing bad golf, you have no idea how you ever did what you did in playing good golf. That scrambles your brains."

As Murray notes, an argument can be made that Casey is the most talented English golfer of his generation. That's a bold statement considering his compatriot contemporaries feature Luke Donald, Lee Westwood, Ian Poulter and reigning U.S. Open winner Justin Rose.

Casey did once sit at No. 3 in the world, though, so he's reached grand heights in the game before. A series of injuries, including a dislocated shoulder, derailed his golf game, and the breakup of his marriage didn't help.

Now, at age 35, it appears the candid Casey has regained his confidence still in the midst of his golfing prime. Casey said, per Murray:

"

It's so easy to dwell on what has happened, the missed cuts, but I would end up being upset, angry and depressed about things. So you can't do that. I won't deny it, there is an element of depression. There is certainly frustration. But it is depressing. This is what I do but it is also what I love. I was not being able to do the thing that I love.

I don't want to do anything else, I'm not qualified for anything else. I want to play golf for as long as I can. Not being able to do that was the worst place in the world.

"

A significant step in the right direction was taken when Casey won his first tournament since 2011 at the Irish Open, eagling the 18th hole to win by three strokes.

That was followed by a tie for 24th at the Scottish Open, and now Casey has had plenty of time to prepare for the year's final major.

Per Murray, Casey feels he's ready to win: "I think I am very ready to win a major, ready for everything that goes with it. Now I just want the golf to be there so that I am back playing the majors the way I want to be. And when I am, I will be enjoying it and appreciative of it but I'll also be there to win."

Considering how hard Casey has fought to get off the proverbial mat, I'm not counting him out this week, even after a modest tie for 27th in Akron.