With four Irish-trained colts going to post for this afternoon's Vodafone Epsom Derby, there has rarely been a numerically stronger green challenge but as challenges go this is all about one AP O'Brien.

Noel Meade's Sunshine Street would be a shock winner but Aidan O'Brien's trio of Second Empire, King Of Kings and Saratoga Springs represent an awesomely gifted challenge from just one yard.

Add to that latent equine talent the almost Hamlin like faith in O'Brien's abilities which paid off so spectacularly yesterday and it's easy to see why hopes are high for a tenth Irish-trained Derby winner since the war.

So very easy to see and yet despite the O'Brien magic, there are nagging doubts. Putting our cards on the table it would be no surprise to see any of the Ballydoyle three win today. They really are that good.

After a winter of ignoring the whispering snakes in the grass who doubted his resolution, King Of Kings put in a spectacular performance to win the 2,000 Guineas in a style that suggests we haven't seen as naturally gifted an athlete in some time.

Saratoga Springs was beaten in France last Sunday but that was on ground he hated and today he is equipped with a visor and Derby-winning rider Willie Ryan in an attempt to rouse his lethargic soul. If it works, odds of as high as 25 to 1 look insulting and oh so tempting.

And then we come to Second Empire who if the grapevine is to be believed is the best of them all. By choosing to ride him, Michael Kinane certainly thinks so and it would be an impertinence by this scribbler to second guess Kinane. Kinane's judgment is usually spot on - Zagreb in the 1996 Irish Derby apart - but the nagging doubt is whether Second Empire's judgment is equally so.

This is a colt with outstanding talent but will he allow himself to show it? Enough ink has been spilt over that ride by Christy Roche in the Irish 2,000 Guineas two weeks ago but what it did show was a terribly fresh colt who paid scant heed to his rider's attempts to make him take life a little easier.

Has the two weeks since been long enough to teach Second Empire to settle because a repeat today will have him spent by the time they reach the straight. Reports from Ballydoyle have not been especially encouraging in that regard and the fact that Second Empire's two colleagues from the A-Team also take part leads one to believe there is little confidence about Second Empire nonchalantly ignoring the Derby day buzz and walking out of the stalls.

If however, he does do all that, and the first major climb away from the stalls should be a help, Second Empire and the 1998 Derby will probably be forever inextricably linked. That is a big if.

A Derby victory by Second Empire, or either of O'Brien's other colts, would be momentous for 28-year-old O'Brien but that big if leads us elsewhere for a possibly more reliable selection. Cape Verdi is an outstanding filly, especially considering she best Shahtoush by five lengths, but is she that outstanding that she can defy history and become the first of her sex to win since Fifinella in 1916.

In an above average Derby like this it must be doubtful. Her stablemate City Honours has the looks of a winner but whether his acceleration is commensurate with those looks is questionable. Gulland's Chester Vase looked ordinary while Courteous still looks a little raw for this task. Which by process of elimination hopefully brings us to the winner.

Border Arrow and Sadian have solid each way claims but for winning claims look no further than Greek Dance. This is a progressive colt who may not have beaten much so far but looked impressive doing it and significantly put up a good time when winning at York.

Unlike Second Empire, Greek Dance has had an uninterrupted preparation, is guaranteed to stay and on breeding will have no trouble coping with a cut in the ground should the skies open. The vibes from his connections are also extremely positive which is given even more weight by the pedigree of those connections.

Michael Stoute has won the Derby twice already with Shergar (1981) and Shahrastani (1986).

At 3.45, the heart may say Second Empire but the head will shout Greek Dance. Either will do.

Brian O'Connor's Derby forecast

1 - Greek Dance, 2 - Second Empire, 3 - Sadian Ends