IT was a big morning for Michael Clarke at yesterday's Sha Tin trackwork session. The visiting Australian jockey has been dogged by bad luck since he first arrived in town. He was off for three weeks following a crashing fall from Easy Fit and has found winners hard to come by since his return, conjuring a solitary success from Schnitzer in a 1,200-metre event despite the enigmatic English import hanging in during the closing stages. He clearly gets on well with Schnitzer who was notching only his second career win when getting up to beat California Gold last time out, having been patiently ridden until the last 200 metres in an astute piece of tactical thinking by Clarke. Yesterday he was back on board Neville Begg's Schnitzer and the pair worked conspicuously well from the barriers at the top of the back straight in company with speedy stablemate, Shanghai Star, who is a good guide. Schnitzer pulled clear in the closing stages and looks in good form for Sunday's Class Two 1,200-metre event though this represents a stiff rise in grade. Clarke also put a couple of Wong Tang-ping's through their paces and they are two to most definitely keep an eye out for over the closing seven meetings. Wong has almost certainly trained New Zealand import Winner's Special for a Class Three mile event on Sunday. Winner's Special ran by far his best race in Hong Kong last time out when staying on to be sixth of 14 over 1,400 metres in Class Three. The move to a mile should help considerably and it is noticeable that the intensity of his trackwork has increased in the past three weeks or so. As the intensity has increased - he clocked one minute, 16.4 seconds for 1,200 metres yesterday - so has the quality. Then there is the private purchase griffin, America Supreme, who caught the eye running a strong third in a recent trial down the straight 1,000-metre course. He again worked fluently and powerfully yesterday morning when dominating Call Me Horse and has at least a tierce chance on Sunday in a 1,400-metre contest in which Geoff Lane's Shining Winner, who worked solidly on Wednesday, and Patrick Biancone's Big Mac, who worked well on Tuesday, could provide most danger. Splendid, an unlucky loser behind Gints To Win over 975 metres at the Valley last time when he couldn't get a clear run, continues to progress for the move to joint champion trainer John Moore. The sprinter went very encouragingly with Super Falcon yesterday morning and appears a winner waiting to happen, especially if pushed up to 1,200 or 1,235 metres. Apprentice Raymond S. M. Tam faces a last-minute fitness test to see if he can ride at Sunday's big Champions and Chater meeting after he was lucky to escape serious injury at Sha Tin yesterday. Tam was thrown to the ground when his mount, Happy Go Lucky, collapsed and died at the end of his workout. The Neville Begg-trained grey suffered a massive internal bleeding attack and toppled under the rail at the far end of the back straight. Fortunately Tam was thrown to safety but he limped away and his trainer, David Hill, said: ''It's touch and go whether he can ride. We are waiting to see how he is in the morning.''