Who will win the Congressional medal of honour?
World golf is in a state of flux. The old icons are waning. The top spot in the world rankings is being passed around. The young guns are yet to fire fully.
A quick glance at a few bookies has Lee Westwood or Luke Donald as favourite at about 12-1, followed closely by Phil Mickelson. Rory McIlroy is available in the 20s and then a group that includes Martin Kaymer, Hunter Mahan, Steve Stricker, Matt Kuchar and Dustin Johnson at about 25-1. The ailing Tiger Woods is missing of course - out injured, and out of the world's top 10.
The water is muddied further when you consider seven of the past eight major champions were first-time major winners. Last time out it was South African Charl Schwartzel at the Masters. Each of the last 10 majors has also been won by a different player.
"A few years ago maybe it was 10 or 12 players [who could win] but now it's so spread out. I think it could be anybody - 30 to 40 is my guess," said world number three Kaymer.
Let's start with Mickelson, who will celebrate his 41st birthday on the opening day on Thursday. The left-hander would dearly love to finally land his national title after five runner-up finishes in 20 starts, most recently behind Lucas Glover at Bethpage in 2009. The four-time major champion has been hit-and-miss this season, barring a spectacular win at the Houston Open in April, but he is confident he can fire at the right time.
"When I was trying to win my first major championship, if you focus so much on the result, so much on winning, sometimes you can get in your own way," he said.
"So I'm trying not to think about winning as much as I am trying to enjoy the challenge that lies ahead and the process. Having been in contention so many times through the years, I really believe that I can win this tournament."
World number one Donald must be considered another leading candidate. The US-based Englishman leads the US money list and has finished in the top 10 in his last eight PGA Tour events, and in 15 of his last 16 tournaments. Donald won the WGC Match Play in February and overhauled Westwood at the top of the world rankings when he beat his countryman in a play-off for Europe's PGA Championship.
At 33, Donald is often described as a US Open-type player, well suited to the tight fairways, penal rough and slick greens typically associated with the year's second major.
His best US Open result has been tied 12th in 2006 and he shot 78 in the last round at Pebble Beach last year to finish tied 47th. A generally misplaced accusation is that he isn't long enough - he is ranked 153rd in driving distance with an average of 279.9 yards - to contend at a US Open.
Congressional Country Club's Blue Course will measure 7,574 yards, the second-longest in major history. But length isn't everything. Donald came fourth at the Masters in April and that measured 7,435 yards.
"It's refreshing to see that the game is not being out-powered," said defending champion Graeme McDowell.
"Luke's iron play has always been unbelievable, and I think that's one of the keys. I always knew he had a great wedge game and a great short game and a putting stroke to die for, so he's really got his game polished up and driving it a lot better. He's really got the whole package now."
McDowell (left) and Westwood practise together at Congressional. Photo: Getty
Westwood, the world number two, has been knocking on the major door for a few years, notably at the Masters in 2010. The 38-year-old, who has won three times in recent months, has also had three top-10 US Open finishes, came second and third in the last two Opens, and was third in the 2009 USPGA. It's either a matter of time before he bags a big one, or it's becoming a problem, depending on your view.
An additional pressure for Westwood and Donald is the fact that no Englishman has won a major since Nick Faldo in 1996, or won the US Open since Tony Jacklin in 1970. And there are the constant jibes flying about that topping the world rankings without a major title is somehow less of an accomplishment.
Germany's Kaymer is the defending USPGA champion and took over as world number one from Westwood - who in turn stole Woods's crown last October - in February. Kaymer was seventh at Pebble Beach last year but missed his fourth straight cut at the Masters.
Northern Ireland's McIlroy is back for his first major since his Augusta collapse when he squandered a four-shot lead at the start of the final round, carding 80 to slip to 15th. He bounced back with a third in Malaysia the following week and was fifth at Memorial a couple of weeks ago. But the measure of how much he learnt at Augusta will be if he gets into contention again at Congressional. He was tied 10th at the US Open in 2009, but missed the cut last year.
So what of the American challenge behind Mickelson? For the first time since 1994, no Americans hold any of the four major titles. Since 2000, there have been just four American US Open winners, and three of those were Woods (2000, 2002, 2008). And along with fifth-ranked Mickelson, there are only three other Americans in the world's top 10 - Stricker (4th), Kuchar (6th) and Johnson (9th).
Of the main contenders at Congressional, Stricker has had two fourths and won at Memorial, runner-up Kuchar has eight top 10s and Mahan, rated higher than his 20th ranking, has finished in the top 10 seven times. Then there's Johnson, another player like McIlroy with a point to prove after shooting 82 to blow a three-shot lead going into the final round 12 months ago.
And what of McDowell? Since 1991, only Woods and Retief Goosen have finished better than 40th in trying to defend the US Open. The last to defend successfully was Curtis Strange in 1988-89.
McDowell had a stellar 2010 but has been off colour recently - including blow-outs at both the Players Championship and Wales Open - and admits the burden of being US Open champion has hung heavily.
"Having arrived here I feel a weight has been lifted and I can move on with the rest of my career," said the 31-year-old.
If there is one area that will prove the difference this week, it is the greens. According to the United States Golf Association, they will measure 14-14.5ft on the Stimpmeter. That's known as lightning. Take note - Stricker and Donald rank third and fourth in the PGA Tour's number of putts-per-round stats.
The USGA's philosophy is to make the US Open "the most rigorous, yet fair and complete, examination of golf skills, testing all forms of shot-making". The key at Congressional will be patience, a word you will hear a lot this week.