In some years the Coral-Eclipse Stakes, to be renewed at Sandown on Saturday, passes totally under the radar. Not this time. Not with a pair of immensely gifted three-year-olds, Sea The Stars and Rip Van Winkle, in the line-up.

Rip Van Winkle fits Sir Winston Churchill’s poignant depiction of Russia. He’s a riddle wrapped in a mystery inside an enigma. Invariably, however, all attention gravitates towards Sea The Stars. Can he climb the daunting staircase that leads to the gates of greatness?

History suggests that the answer will be forthcoming on Saturday. The Eclipse may be one small step along the way but the fate of Derby winners delivers an inescapable conclusion. Only the very best of them win it.

Consider the evidence. The last four Derby winners to contest the Eclipse were all beaten. Erhaab sank at odds of 4-6 in 1994, followed by Benny The Dip three years later, Motivator (2-5) in 2005 and Authorized (4-7) in 2007. The latter two were advanced as nascent champions until they fell flat on their faces at Sandown.

It is 21 years since a blue riband winner bridged the Eclipse divide – and it needed an outstanding one to do it. Nashwan’s victory was his third in a sequence that embraced the 2,000 Guineas and the Derby.

In this way has the Eclipse acted as a perfect filter. It sifts out Derby winners with overblown reputations from those who really have what it takes.

Further exploration of the Derby-Eclipse challenge only emphasises the point. Two years before Nashwan, Reference Point failed in the Eclipse. The litmus was accurate once more: Reference Point’s subsequent exploits identified him as a very good Derby winner, but not a great one.

The difficulty in completing the double almost certainly rests with the physical immaturity of three-year-olds in relation to their elders at this time of year. The weight allowance they receive in consequence only partially compensates.

Three-year-olds are akin to the annual college draft in American football. The best of them command a fortune even though they have yet to prove themselves in the unyielding world of gridiron. Some draft picks flourish, others founder. And some picks lower down the draft end up as top-dog.

In a similar vein, some Derby winners fail the Eclipse test but rebound later in the season, as they develop physically, to show their true worth. Reference Point was a case study. But the beauty of the Eclipse is that the physical advantage rests with the older horses. Only a vastly superior three-year-old can surmount it.

Here’s one more ringing endorsement of merit of the Derby-Eclipse test. Prior to Nashwan, the last Derby winner to win the Eclipse was Mill Reef back in 1971. The great Mill Reef: a post-war icon of racing; subsequently winner of the King George and the Arc.

These are the heights to which Sea The Stars aspires on Saturday. He is an odds-on shot – but that’s largely because he is youth’s glamorous representative, the coming force, the horse with a reputation unsullied by defeat.

The portents for victory appear promising. Like Nashwan before him, Sea The Stars has won the 2,000 Guineas and Derby en route. Nevertheless, as decreed by the folios of history, the Eclipse is his stiffest test yet.