Woods beat May by one stroke in that extra session to repeat as champion, but there is a chance neither player will tee it up this week.
May didn't qualify and Woods injured his back in Akron last week. If Woods fails to start the championship, it will mark the 26th straight major which he didn't win and it will be the seventh major that he missed among those 26.
There may be plenty of questions about Woods, but there is no questioning Rory McIlroy. The new world No. 1 beat Sergio Garcia at the Open Championship and last week at the WGC-Bridgestone Invitational.
McIlroy has made the cut in all five of his PGA Championship appearances, and has finished inside the top 10 in four of those five. He enters the year's final major having broken par in 12 of his last 14 rounds. In those 14 rounds, the 2012 champion is 38-under par.
Valhalla also hosted the 1996 PGA Championship, where Mark Brooks beat Kenny Perry in a playoff. Both are in the field this week, and Perry will have huge crowds following him as he hails from Franklin, Kentucky.
Since hosting the 2000 PGA Championship, Valhalla has hosted a pair of Senior PGA Championships as well as the 2008 Ryder Cup, where the United States beat Europe, 16 1/2 - 11 1/2. That is the Americans only win in the last six Ryder Cups.
While there was plenty of drama at the last two PGA Championships at Valhalla, the seasons first three majors haven't had nearly as much drama.
Bubba Watson jumped into the lead on the front nine at Augusta, then cruised home to win his second Masters title. He was hardly threatened on the final nine.
Martin Kaymer opened 65-65 at the U.S. Open en route to a dominating 8-stroke win.
Last month, McIlroy beat Garcia and Rickie Fowler by two strokes at the Open Championship. However, McIlroy led by six entering the final round after closing with two eagles in the last three holes of the third round.
McIlroy flew into the lead at the WGC-Bridgestone Invitational with four birdies in the first five holes. Garcia later tied him in the lead, but McIlroy birdied the 11th to regain the lead and Garcia bogeyed the 15th to fall two back. McIlroy finished the win with seven pars in a row.
While McIlroy is on fire, there are plenty of question marks among his competitors. Woods is an obvious question mark with his back injury, while another potential top finisher, Jason Day, withdrew from the WGC-Bridgestone Invitational due to dizziness.
Phil Mickelson finished inside the top 10 the last two times the PGA Championship was at Valhalla, but that is one more top 10 than he's had all year.
Henrik Stenson won the season-ending events on both the PGA and European Tours last year, but hasn't won since. Justin Rose won a pair of events a month ago, but he has made the cut in only six of 11 PGA Championship starts.
Matt Kuchar and Kaymer have made the cut in just three of their six PGA Championship starts, though Kaymer did win the 2010 PGA in a playoff and he won this year's U.S. Open by a mile.
While some of those top competitors struggle, Adam Scott and Rickie Fowler are among those playing well heading to the season's last major.
Scott lost his No. 1 ranking to McIlroy, but has run off five straight top-10 finishes, including at both the U.S. Open and the Open Championship. That run started with a playoff win over Garcia at Colonial.
Though he hasn't won since the 2012 Wells Fargo Championship, Fowler is the only player to finish inside the top 5 at the first three majors. In his last four starts, he shared second twice and tied for eighth twice.
That is how some of this year's competitors are doing, but what about last year's winner? Jason Dufner is still looking for his first win since he won at Oak Hill last August.
Dufner rallied with a 2-under 68 in the final round last year to leap over Jim Furyk and win his first major championship. Two years earlier, Dufner had lost to Keegan Bradley in a playoff.
As for this season, Dufner has missed three cuts, two of which came in major championships. He tied for 51st at the Open Championship, so he has been a non-factor in the majors.
While some of the top competitors are struggling with their games, one potential challenger will not be in the field this week. Dustin Johnson, who was penalized at the 2010 PGA and lost his spot in the playoff, withdrew from the championship.
Johnson reportedly failed a drug test and is taking a leave of absence from the tour. He has also taken his name out of consideration for the Ryder Cup in September.
Outside a few select players, the field is wide open this week. Will one of the few hot players, like McIlroy, continue to roll or will someone come from out of nowhere to win his first major?
That seems unlikely as Valhalla has produced four established winners - Mark Brooks, Woods, Hale Irwin and Tom Watson.
Look for another battle between McIlroy and Fowler come Sunday.