Outside the audacious, yet magnificent, red-bricked clubhouse with its Byzantine connotations here at Medinah Country Club, there are car-park spaces reserved for those players competing in the 88th USPGA Championship.

Contrary to the prevalent impression that there are just two players - you know, Tiger and Phil - competing in the event commonly known as "Glory's Last Shot", the truth of the matter is 156 spaces are retained.

And, to be sure, this championship is far more open than just a duel between the big two. Sure, Tiger Woods, the British Open champion and world number one, and Phil Mickelson, the US Masters champion and world number two, are the favourites.

Sure, they both bring with them an aura into the majors nobody else in golf's modern age can match. Sure, they're great players, one who discovered the art of accruing major titles early in his golfing career and the other who took a little longer to do so.

Between them, they've won six of the last 11 majors. But the truth of the matter is there are at least a dozen other players, not to mention the odd springer or three liable to jump from the anonymous pack, well capable of challenging the sport's two most dominant personalities.

After all, this is a field that includes 95 of the top-100 ranked players in the world, so in depth quality is not an issue.

Sure, most eyes here will be on Woods and Mickelson.

As US Open champion Geoff Ogilvy, the meat in the sandwich of a gloried three-ball that also groups Woods and Mickelson together for the first two rounds, confessed, "I'm sure it will be a zoo," before adding, "But I've always played well when playing with Tiger, or with Phil. When you play like I have this year, you come to tournaments like this believing you can do really well and being disappointed if you don't."

Such self-belief will be required by anyone attempting to usurp Mickelson, the defending champion, or Woods, who has won his last two tournaments.

With the withdrawals of Darren Clarke and Paul McGinley from the championship, Padraig Harrington and Graeme McDowell - part of a strong European contingent seeking to end the continent's major drought - are the only Irish representatives.

Harrington and McDowell are resuming tournament play after a two-week break; and with Harrington, who finished tied-fifth in the US Open at Winged Foot in June, there is a level of confidence that suggests he could be one of those to challenge and ensure Messrs Woods and Mickelson don't have things entirely their own way.

"I think the course is very straightforward, a bit like Winged Foot," observed Harrington. "You hit it in the fairway, hit it in the middle of the greens. The greens are quite small, very traditional, and it's just a very fair and very tough golf course."

Although he hasn't yet won this season, Harrington claimed, "I've felt good about my game all year. I'm a much better player than I was last year. It's just a strange game. I've changed some things this year and I'm putting the lack of wins down to transition more than anything else. But I feel really good about my game and I think I'm very confident. I've probably never been as confident or relaxed going into tournaments this year, (and) maybe I need to go back to a fearful panic before a tournament."

He added, "When it comes to winning tournaments, you want to be in contention as often as possible and I haven't really done that this year. So, you know, to give myself a chance of winning this week you'd like to have been there in the heel of the hunt a few times and to be sharp for that.

"I like the golf course. It won't necessarily suit any particular style of play. Everybody's got a chance here, whoever turns up with their game."

The course, measuring 7,561 yards, is the longest in major championship history; but it won't play as the longest, because of the amount of run on the fairways.

Woods, for one, doesn't believe he will use driver on more than six or seven occasions, and four of them will be on the par fives: "I'm not going to hit many drivers, because the course won't allow me to. Most of the (par four) holes are dog-legged. I'd have to take driver over the top of the tall trees and that doesn't make any sense."

On the last occasion the USPGA was held here, Woods famously held off the charge of Sergio Garcia coming down the stretch. Changes have been made since then, however,  with seven greens rebuilt, among them the 17th, where the tee has been moved back and the green now positioned behind the lake, which is now very much in play.

But Woods, like Harrington, likes what has been done. "It's old and traditional and just very straightforward," he said. "You've got to hit the ball well and obviously control your irons into these greens in order to have a chance."

A bit of a minor rumpus developed in the run-up to the championship, Mickelson's short-game coach, Dave Pelz, observing, based on his own statistics, his man was better than Woods.

"When Phil is at his best, I'm thinking nobody can beat him," said Pelz. To which Woods, equally candidly and not batting an eyelid, replied, "I'm pretty tough to beat when I'm playing well too."

Certainly, the fact Woods and Mickelson have been paired together is something that adds spice to the season's final major, a championship that will decide the final make-up for the US team for the Ryder Cup at The K Club next month.

Neither Woods nor Mickelson, though, has to worry about his place, which is already secured. For them, it is a matter of focusing only on this event.

Even Chris DiMarco, runner-up to Woods in the British Open at Hoylake last month, is intrigued: "They're two competitors that are constantly trying to beat each other's brains in week-in and week-out.

Tiger is number one, and Phil is trying to become number one."

The head-to-head between Woods and Mickelson with Ogilvy as the odd man out will certainly add to the intrigue over the first two days.

But majors are never won on a Thursday or a Friday; and the sideshow between the big two could well prove a distraction, allowing others to manoeuvre into positions for the weekend. And, really, that's the way it should be.