But chances of seeing a Grand Slam winner this year ended earlier in the week when Nick Skelton's stallion Big Star was ruled him out of the Canadian event.
Skelton had won the Aachen Grand Prix but an injury to his horse put an end to his hopes of winning the million euro prize offered by Rolex.
Big Star could still return for the final instalment of the competition in Geneva and if so Skelton could still claim the 250,000 euro prize for a rider who wins two non-consecutive legs of the three.
While Skelton misses out, Calgary will still welcome some of the best riders in the world, including Olympic champion Steve Guerdat of Switzerland and recently-crowned European champion Roger-Yves Bost of France.
Also expected to be in the mix is the young winner of last year's edition, Belgian Olivier Philippaerts who is back with Cabrio Van de Heffinck, and Germany's world number one Christian Ahlmann.
Up for grabs in Calgary is one million Canadian dollars for the winner of the Grand Prix, in addition to any potential Grand Slam prize money.
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