FORMER triple champion jockey Basil Marcus is virtually certain to be fit to ride the brilliant Mr Vitality in the feature Happy Valley Trophy at tomorrow night's opening meeting of the $1 billion revamped city track. Marcus took a heavy fall and was detained in hospital overnight when his mount California Gold stumbled and threw him out the side door in the second event at Sha Tin on Wednesday night. But the tough-as-teak South African has passed numerous scans and X-rays in the last 24 hours and his mandatory Jockey Club medical this morning should be little more than a formality. 'He's 90 per cent sure to ride,' confirmed his retaining trainer Ivan Allan last night. Marcus will also ride trackwork tomorrow morning just to give himself a thorough blowout. In the unlikely event of any adverse reaction to the fall, Allan has taken the trouble of booking multiple New Zealand champion jockey Lance O'Sullivan as a standby declared rider for Mr Vitality in the feature event which will be watched by the incoming chief executive of the Jockey Club, Lawrence Wong. Wong will be one of thousands who flock to the Valley to see the new track officially opened. The punting public will be desperately keen to see the unbeaten Mr Vitality in action prior to his crack at next month's showpiece $5.5 million International Cup. Last night Allan was keen to run Mr Vitality, with or without Marcus, as the horse needs another run to bring him to peak condition for the International Cup. 'But should the unlikely happen and Basil not pass his medical, I won't be able to make a final decision about his participation until I've spoken to his owner in England tomorrow evening,' Allan added. Marcus yesterday confirmed that his mount California Gold did not clip heels when falling on Wednesday, contrary to the official stipendiary stewards' report. The stipes, without interviewing either of the jockeys concerned, stated that California Gold had clipped heels with Super Structure. O'Sullivan, Super Structure's jockey, endorsed Marcus' point. 'There was no contact and no one asked me if there was,' he stressed. But the video replay shows the track was not to blame. California Gold just slipped and lost his footing as can happen in a race. Meanwhile, ebullient local owner Sunny Yam flies out to Japan this afternoon with his hopes high of watching his top colt, Danewin, run into the placings in Sunday's prestigious Japan Cup. Danewin, a multiple Group One winner in Australia, will be ridden by local jockey Jackie C.K. Tse who has already won two Group One events on the Danehill colt in Sydney. Yam said yesterday: 'I've just finished speaking to my trainer and he tells me that our horse has taken the trip well. 'It would be fantastic if he and Jackie can win and bring the glory to Hong Kong. We are hopeful he can run in the first three. 'It would be a great achievement.' Tse will have at least one ride on the expansive Toyko course, which has a 700-metre run-in, prior to the Japan Cup. Former Hong Kong kingpin, Gary Moore, has told him that the best ground in the straight is often out wide and Tse will also seek the advice of the English and Irish Derby-winning jockey, Alan Munro, who is on his second three-month stint in Japan.