THE fences may be smaller and the distance nearly half- a-mile shorter than its Aintree cousin, but the Scottish Grand National is still a formidable challenge for those who seek to etch their names alongside some of the great steeplechasers to have landed to prize.

A fleeting glance at Ayr's roll of honour is sufficient to illustrate the qualities required to triumph: fluent, accurate jumping, copper-bottomed stamina and bundles of courage to get the job done when the chips are down.

A bronze statue of Red Rum stands outside Western House next to the Ayr course, serving as a permanent reminder of that legendary horse's remarkable deeds in the spring of 1974, when he won at Aintree and then Ayr, both times under top weight.

To this day, he remains the only challenger to complete the Grand National double in the same season.

Not even Ray Green, the wonderfully enthusiastic owner of Merigo, would consider mentioning his charge's name in the same breath as Red Rum. Even so, a small piece of history beckons this afternoon as the 2010 winner seeks to become the first horse to reclaim the Scottish National crown since the four-mile race moved to Ayr from the now-defunct Bogside course in 1966.

Few, if any, chasers of the modern era have seemed so suited to the Scottish National than the 11-year-old. Ever since Merigo failed narrowly to claim back-to-back victories 12 months ago, his trainer Andrew Parker has focused his energies on priming him for today.

A confidence-boosting win at the course last month advertised his wellbeing and another bold bid for glory looks assured. Dangers abound, none more so than Harry The Viking, his fellow 7-1 favourite.

Paul Nicholls' progressing chaser will not lack for stamina or support as the Manchester United manager Sir Alex Ferguson, one of his co-owners, is making the trip back to the town where his playing career ended in 1974 to cheer him on.

The race represents a significant test for the inexperienced seven-year-old – it is only his fourth appearance over fences – but there are others capable of denying Merigo a repeat success.

Knockara Beau has been mixing it with the best this winter, most recently when beaten less than 20 lengths in the Gold Cup. Talented and tough, George Charlton's charge has always threatened to land a decent prize. If he stays today's longer trip and cuts out occasional jumping lapses, this could be it.

Ikorodu Road, who is closely matched with Harry The Viking on handicap ratings, won valuable races at Doncaster and Newbury in his last two outings.

And Portrait King proved he handles good ground as effectively as he does softer conditions with victory in Newcastle's Eider Chase in February although no Irish horse has won the Scottish National since it transferred to Ayr. Quentin Collonges and Fruity O'Rooney also have chances in a wide-open renewal.