Winning back-to-back US Opens is very, very hard to do. Tiger Woods never managed it. Neither did Jack Nicklaus. Arnold Palmer only won the tournament once.
That's why when Curtis Strange managed to pull off the feat in 1989 - following up his victory at Brookline in 1988 with a successful defence at Oak Hill - golf's greats doffed their caps with an extra flourish.
The six-man club of Willie Anderson (1903-1905), John McDermott (1911-1912), Bobby Jones (1929-30), Ralph Guldahl (1937-1938), Ben Hogan (1950-51) and Strange added a seventh member in 2018.
Brooks Koepka took the title with a very un-US Open score of 16-under at Erin Hills in 2017 but showed he could tough it out in the tournament's trademark brutal conditions when winning again at Shinnecock Hills with 1-over 12 months later.
After his dominant six-shot victory at Winged Foot in September, Bryson DeChambeau will be looking to become the eighth member of the back-to-back gang when he tees it up Torrey Pines in 2021.
In theory, a California venue for a Californian golfer looks ideal and Torrey Pines South is well known to DeChambeau from his junior days.
But his record there as a pro doesn't seem to bode well for his US Open defence bid: he's played the Farmers Insurance Open at Torrey Pines twice and missed the cut both times.
Perhaps because of that questionable course form, DeChambeau is currently 14/1 fourth favourite with William Hill to win the US Open for a second year running.
Ahead of this week's Valspar Championship, golf's biggest hitter took part in a US Open Media Day.
The 27-year-old gave his views on several things, including Tiger's incredible victory on one leg at Torrey Pines in the 2008 US Open and the strategy he used to win the 2020 Open at Winged Foot.
But perhaps, in terms of him winning the US Open again this year, he left us with more questions than answers.
On Tiger's infamous victory at Torrey Pines in 2008
"One of the most impressive things that I remember from that is the fact that Tiger, being Tiger, having fractured a leg and all that, literally still going after it and playing the full 72 holes and then going out and playing another 18 holes after that (beating Rocco Mediate in a playoff).
"It's something that I can't fathom doing and how much pain he went through, how much struggle and strive and agony he went through, all that pain, and to come out on top is something that is unfathomable, something that allowed me to say, hey, if he's going through that much pain, through that much trouble, that much strife and still able to come out successful and win a golf tournament, win the US Open, it has inspired me to work even harder.
"It's inspired me to almost say, hey, if he can win off of a broken leg pretty much, what can I do if I work hard. It's inspired me to a whole other level.
On his previous missed cuts at Torrey Pines and why he didn't play there in January
"Yeah, you know, look, I've played well there before. I finished third in Junior World and, no, it was second in Junior World actually. I've played well there before. The times that I was there for the Farmers Insurance, my game wasn't on point. I wasn't comfortable with how I was playing when I was there for those years. I wanted to play this year. I had too many things going on with my schedule and ultimately just didn't work out for me to play this year.
"But look, the golf course will play completely different when the US Open comes around this time. The golf course is going to be really firm, fast, long enough, I'm sure, and I think that the Farmers plays a little bit different.
"But I love the golf course. I love the tournament, and I'm sure I will be back here soon."
Responding to comments from Xander Schauffele that the US Open setup in 2020 was like a pitch-and-putt and had played into DeChambeau's hands
"Well, look, I don't think it was a pitch-and-putt for sure. I still had to hit shots. There was a shot I hit on No. 5, it was a 6-iron out of the bunker. But for the most part, yeah, I was able to hit pitching wedge out of the rough where people were hitting 6-irons and 7-irons out of the rough just laying up.
"So for me, starting out the week, I was like, there's no other way to play this golf course than hitting it really far and just wedging it out to the green. So it really wasn't a pitch-and-putt because I still had 40-footers that I made, 30-footers that I made.
"But for the most part getting the fairways that tight made it very easy for me to make my decision to hit driver off the tee as far as possible."
On what it takes to hit out of thick rough - something Torrey Pines is known for
"It really depends on the type of grass. So for example, if I'm hitting out of kikuyu, there's almost no club you can get it out with hitting it really far. If it's deep down into the rough in kikuyu, it's almost impossible to get out of.
"If it's ryegrass (the dominant strain at Winged Foot), that's a different situation. It could be down to the bottom, base level of the ground and you can still get it out for the most part. But pitching wedge or 9-iron, about 45 feet of loft for you to get it out and have enough ball speed to get the ball up to a green.
"I mean, we go (to Torrey Pines) and practice that week to see if it's feasible to hit 7-irons out, if it's feasible to hit pitching wedge out of it, if it's feasible to hit 4-iron out of it even, and if it's not, then we literally have to change our dynamics and our course thought depending on where long rough is, where I can essentially hit it."
On whether Torrey - with its kikuyu rough - suits his game and what his approach will be
"Well, I would say for the most part - look, any type of rough - it depends on how wide the fairways are. That's what I'll say. If the fairways are super tight, no matter what, we're all going to be hitting out of the rough, and whoever can play out of the rough is going to probably have success.
"Kikuyu, it just depends on the lie that you have. If you're rolling it into the rough versus flying it in and hitting it down into the rough, it depends on how much the golf ball is going to be going into the ground. You don't want that golf ball going to the ground in kikuyu.
"So definitely it depends on the golf course we're playing and the type of rough that's out there."
Is DeChambeau a good bet for the 2021 US Open?
As well as having history against him, there's a niggling feeling in DeChambeau's answers that Torrey Pines could offer problems.
Recently, Rory McIlroy made headlines for saying that trying to be like Bryson and smash the ball greater distances had had a detrimental impact on his game.
Somewhat lost in those juicy quotes was a comment Rory made about DeChambeau's ability to hit out of the long grass.
"The one thing that people don't appreciate is how good Bryson is out of the rough," said McIlroy. "Not only because of how upright he is but because his short irons are longer than standard, so he can get a little more speed through the rough than us, than other guys."
At Winged Foot an excited DeChambeau said this after playing the course in practice: "Even if it's in the rough, I can still get it to the front edge or the middle of the greens with pitching wedges or 9-irons. That's the beauty of my length and that advantage."
But with DeChambeau admitting that deep lies in kikuyu are almost impossible to smash out of, it appears some of that obvious advantage has gone.
In which case, Torrey's kikuyu could be this particular superman's kryptonite.