Cut short: four stars who never got the chance to realise their full potential

Too Darn Hot was an exceptional two-year-old but after delivering in style in the Sussex Stakes at Goodwood last week, there was a feeling that he may yet have scaled even greater heights before the end of his three-year-old season.

Unfortunately the prospect of a possible return to sprinting or a crowning moment at the Breeders' Cup was snatched away with the news on Monday that he had sustained a career-ending injury and will now transfer to stud following his recovery.

He is not the first top-notch performer to have had his career cut short, with a string of hugely talented individuals lost to the racecourse at the height of their powers and, in many cases, before their true potential had been reached.

Harbinger enjoying life after racingCredit: H Yamanaka / Shadai Stallion Station

Harbinger
Race record: six wins from nine starts
Wow factor: put up one the greatest ever performances in the 2010 King George at Ascot with an 11-length romp

Harbinger had a perfect one from one record at the highest level but had injury not intervened, the question remains just how good might he have been?

The epitome of an improving older horse campaigned by master trainer Sir Michael Stoute, Harbinger came of age in his four-year-old season with four straight wins.

Climbing racing's pyramid one step at a time, Harbinger won a brace of Group 3 contests, before blitzing his rivals with a convincing Group 2 success in the 2010 Hardwicke Stakes.

The next logical step was the Group 1 King George VI And Queen Elizabeth Stakes back at Ascot and a showdown with Derby hero Workforce, Irish Derby victor Cape Blanco and old warrior Youmzain.

Despite his age, Harbinger was in many ways the unexposed runner in the race and he duly put on a performance that was as brilliant as it was breathtaking as he scored by an astounding 11 lengths.

That one performance sent his official rating rocketing from 123 to 135, elevating him to superstar status as officially the best horse in the world. It also raised the question of what level might he be able to reach considering this was his first Group 1 attempt on only his ninth career start.

Unfortunately, that question was destined never to be answered as he sustained a hairline fracture of his near-fore cannon bone during his preparation for the Juddmonte International that ended his racing career all to soon.

Not a moment too soon: Sea Of Class gets up to win the Irish OaksCredit: Caroline Norris (racingpost.com/photos)

Sea Of Class
Race record: four wins from seven starts
Wow factor: came from last to first in the Irish Oaks and came oh so close to doing the same in last year's Arc

Sea Of Class was undoubtedly among the best of her generation at three but painfully we will never know how high she might have been able to fly as a four-year-old and beyond.

Her loss only last month is still raw but there is no doubting this was a filly of rare talent, as she proved both in victory and defeat in her Classic year.

Her performances to win the Irish and Yorkshire Oaks were majestic, coming from off the pace as she sailed past her rivals like a luxury yacht cutting through clear water.

Unfortunately the waters were anything but clear in last year's Arc, instead having to navigate a poor draw and a wall of traffic. Somehow she almost managed it, thundering down the outside to give the mighty Enable a rare fright.

This year was geared to an Arc rematch yet tragically we will never find out who might have come out on top with Sea Of Class succumbing to an aggressive bout of colic.

A rare talent, Sea Of Class will not be forgotten easily and it is a fitting tribute that she is mentioned in the same breath as Enable.

Dubai Millennium
Race record: nine wins from ten starts
Wow factor: take your pick from a six-length win in the Dubai World Cup and eight-length masterclass in the Prince of Wales's Stakes

The apple of Sheikh Mohammed's eye, Dubai Millennium was in many ways the perfect thoroughbred – his doting owner certainly thought so.

Bold and powerful, Dubai Millennium was a majestic animal with a stride that appeared to stretch for miles and a coat that gleaned like the sun. He was also a sensational racehorse.

His only defeat on the track came in the 1999 Derby, with his nine other appearances all ending in victory. He won Group 1 races in France, Dubai and Britain, with his crowning moments coming in the Dubai World Cup and Prince of Wales's Stakes in 2000.

Such was the admiration for Dubai Millennium by Sheikh Mohammed, the owner craved a showdown with Coolmore's champion Montjeu, with talk of a match race to rival Seabiscuit and War Admiral surfacing as the media whipped up a frenzy.

Cruelly, what may have been one of the greatest ever showdowns never materialised, with Dubai Millennium suffering a leg fracture in training that ended his career.

He was retired to the Dalham Hall Stud but shortly into his stallion career he suffered a crippling bout of grass sickness and, despite three operations, was unable to be saved.

While he may have fulfilled much of his promise on the racecourse, the sport suffered greatly by the fact his second career as a sire barely got off the ground.

King's Best
Race record: three wins from six starts
Wow factor: looked a miler of immense quality with a sublime Classic success in the 2,000 Guineas

King's Best was a fabulous Classic winner yet there is little doubt he only fulfilled a fraction of his true potential.

Kieren Fallon described him as one of the greatest he had partnered in his illustrious career after he beat the closest of his 26 rivals by three and a half lengths in the 2,000 Guineas 19 years ago.

Incidentally, that closest rival was none other than the 'iron horse' Giant's Causeway, who was no match for the regal King's Best on only his fifth career outing. At that stage, the boundaries were endless.

Forced to miss the Derby at Epsom, King's Best instead headed for the Irish equivalent and a match-up for the ages against Derby hero Sinndar but his first try at a mile and a half sadly got no further than halfway before he was pulled up with an injury severe enough to end his career.

While he never reached his peak on the track, he subsequently sired Derby and Arc winner Workforce, also trained by Sir Michael Stoute, before colic claimed his life earlier this year.

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