By James Toney in Del Mar

Aidan O'Brien and City of Troy bravely struck out for a new frontier but they'd be no Breeders' Cup gold in the Wild West.

O'Brien has politely answered every media enquiry this week, smiling his way through the repetitive questioning about whether his star would take to a new surface, on a new continent, against new opposition.

The answer was, unfortunately, a resounding no on all counts but you have to respect O'Brien and his Coolmore connections for even trying - with now 18 attempts and counting to win the world's greatest age-for-weight dirt race, the Breeders' Cup Classic, you can't fault their determination.

Racing needs these storylines and there is no shame in this defeat either, for a few days the 'will he, won't he' narrative fuelled the headlines - and being talked about is no bad thing, even if, ultimately, there would be no validation of the bold endeavour.

In the gilded age of horse racing, challenges such as these were common place. It was 101 years ago that the Epsom Derby winner, Papyrus, squared off against the Kentucky Derby winner Zev - the first race ever broadcast live on radio and, perhaps, a forerunner to the Breeders' Cup, which brought more international runners to the US this year than ever before.

Papyrus didn't win that day either and plenty since have tried and failed to crack America too.

O'Brien had plotted and planned every detail of this mission improbable, starting with a full-scale training trip to Southwell for his Derby winner just a few weeks ago, with over a 1000 believers turning up just to watch him gallop.

"We've looked under every stone, we hope there isn't one we haven't found," he said, pre-race.

But you don't need to be a sage studier of form - or a casual inspector of rocks - to know where this bid fell short, racing from stall three meant Ryan Moore needed to be quick on the draw from the start but when the bell rang and he reached for his holster, the rest were already firing clear.

"I didn't have him prepared quick enough to come out of the stalls," admitted O'Brien, classy as ever in defeat and the first to congratulate Chad Brown, trainer of winner Sierra Leone.

"We thought he was quick but he was left three or four lengths behind and it gave Ryan no chance. I should have had him coming out quicker and travelling quicker but we are learning all the time.

"When you are that far back on a dirt surface there is nothing you can do about it. We will try harder next time. When we brought him to Southwell, we got the other horses to lead him but perhaps we should've let him do the leading. It was very sporting of the lads to try and do it and we'll just look forward to his babies now."

However, this 48 hours in California has only underpinned the strength in depth in Irish racing - from trainers to jockeys to breeders.

O'Brien took his tally of career winners to 20, following the success of Lake Victoria and Henri Matisse on Future Stars Friday. It moves him level with legendary American trainer D. Wayne Lukas and he'll be odds-on to be in a league of his own when this track hosts again next year.

Ger Lyons became the sixth Irish trainer to win at the Breeders' Cup as Colin Keane - who collects his Champion Jockey title at the Curragh on Sunday - claimed his second career win with a brilliant ride on Magnum Force, only Ireland's Mick Kinane and Jonny Murtagh have won more at the meeting.

There were four Irish-bred winners - more than any other nation apart from the hosts - with Godolphin's Dubawi colt Rebels Romance delivering the 51st since 1984 in Saturday's Turf.

And County Galway's Rossa Ryan won his first Breeders' Cup race on Ralph Beckett's long-shot Starlust in the Turf Sprint, just 26 days after storming to the Prix de l'Arc de Triomphe in Paris.

"I actually spoke to Ryan Moore before the race about just a little bit of guidance and everything," he said. "Ralph left it up to me, filled me up with a lot of confidence going out.

"It was just one of those days and luck was on our side. This horse has been knocking on the door all year. It's great to see him finally do it on the big stage. He's been a bridesmaid, so this is brilliant and unbelievable."