Top local jockey Howard Cheng Yue-tin has returned a positive random urine test for ephedrine and methylephedrine from the April 1 meeting at Sha Tin but may still be cleared to take his place at Sunday's meeting. The club's chief analyst, Dr Terence Wan See-ming, informed the stewards yesterday that Cheng's sample contained ephedrine and methylephedrine 'above the prescribed thresholds'. When told, Cheng waived his right to have the B or unused portion of the sample tested independently, which will bring the matter to a much speedier conclusion. Complicating, or perhaps clarifying the situation, Cheng was randomly selected for a urine test at Monday's Sha Tin meeting, too. So, although he has technically been stood down from riding as is standard practice, he may be declared clean to ride on Sunday at Happy Valley as a result of that most recent test, and stewards will allow him to be declared for runners when the fields are taken tomorrow. Stewards will decide later, when Monday's test result is known, whether Cheng can fulfil those engagements, and a date has yet to be fixed for an inquiry into the positive finding.