What's the greatest achievement in the history of sports?
Is there a more difficult question for any fan to answer? It's such a subjective and divisive topic, and one that cannot truly be measured.
But that doesn't mean it's not fun to argue the toss nonetheless and on this day 20 years ago, Tiger Woods staked his own claim for the moniker by completing the unthinkable.
It was on April 8, 2001, when Woods won the Masters for a second time and by doing so he became the first player to ever be in possession of all four of golf's major trophies at the same time.
Because it was done over two seasons, Woods missed out on a calendar Grand Slam so the phenomenal achievement was dubbed the 'Tiger Slam'.
"It was exciting for everybody," four-time major winner Laura Davies recalled when speaking to Stats Perform News.
"I'm sure it was hard work for him and very mentally difficult for him to win all four in a year. It was just exciting to watch Tiger do it.
"It just would have been lovely if he'd done it in one year because it's not quite the same but it's still some achievement to hold all four at one time.
"It was good for the game definitely. I'm a big Tiger fan, I love watching his golf. At the time it was just really exciting and just making golf a more exciting game, more exciting for the younger fans and the game's built because of what he did then."
What Woods did transcended the game and enshrined his name even deeper within the list of all-time sporting greats.
Sadly, Woods will not be at Augusta – where he is a five-time champion – this week due to the injuries he suffered in a serious car accident in Los Angeles in February.
But the magnitude of his achievement will stand the test of time and, two decades on, we have taken a look back at the incredible 'Tiger Slam'.
U.S. Open 2000: Taking apart Pebble Beach
"My words probably can't describe it, so I'm not even going to try."
While Ernie Els, who took a distant share of second at the 2000 U.S. Open struggled to sum up Woods' utter domination at Pebble Beach, we should probably at least try.
Having already blasted into a six-shot lead through two rounds thanks to scores of 65 and 69, it was on the Saturday where Woods' class really told.
As the rest of the field struggled badly in wild playing conditions, Woods recovered from a triple bogey at the third to finish the round at level par and take the lead by 10 strokes – the largest 54-hole advantage at a U.S. Open.
If that's not impressive enough for you, then a closing 67 meant Woods was 15 shots clear of Els and Miguel Angel Jimenez. And, no, that is not a typo.
The Open 2000: Sensational at St Andrews
There was a sense of deja vu at The Open just a month later.
There was a sense of deja vu at The Open just a month later.
Poor gags aside, it truly was remarkable to see Woods in full pomp completely in command of the Old Course at St Andrews – the spiritual home of golf.
Opening with a 67 to sit one shy of leader Els, by the end of Friday's play Woods was three shots clear. By the end of Saturday that lead had doubled to six.
A closing 69 wrapped up victory by eight from Els and Thomas Bjorn, with Woods becoming the youngest person to complete golf's Grand Slam in history.
"It wasn't long ago when I said there'd never be another Jack Nicklaus but we're looking at one. He is the chosen one," Mark Calcavecchia said of Woods at the time.
US PGA Championship 2000: Play-off glory at Valhalla
There wasn't quite the same level of domination for 2000's season-ending major at the US PGA Championship but there was a familiar outcome at Valhalla.
Having led or co-led through three rounds, there was a ding-dong battle on the final day with Bob May, who missed a crucial birdie putt at the 15th on the same hole Woods made a clutch par.
Another gain from Woods at the 17th left them tied going up the last. May drained a 15-footer for birdie, but Woods sank his own pressure putt to force a three-hole play-off.
A birdie at the first additional hole was followed by two pars and that proved enough for Woods to join Ben Hogan as the only player to win three majors in one season.
"Tiger plays a different game than we play," May said after his defeat, with Woods saying of the win: "We never backed off. We went birdie-for-birdie, shot-for-shot. It was a very special day."
Masters 2001: The Tiger Slam
After opening with a steady 70, Woods was five shots back of first-round leader Chris DiMarco but scores of 66 and 68 had him leading by one from Phil Mickelson heading into the final round.
Mickelson was part of a star-studded leaderboard including Calcavecchia, DiMarco, Angel Cabrera, David Duval and Els – all of whom were within three of Woods.
Duval made a good fist of the challenge and even briefly tied for the lead by birdieing the 15th – only to give that shot straight back.
Needing only a par at the last, Woods finished with a birdie for a two-shot win to complete a truly epic moment of sporting history.