TOP SPRINTER PUT DOWN David Nicholls` stable suffered a cruel blow when Tayseer was put down after sustaining a serious leg injury during a gallop in Dubai this morning.Tayseer won eight races, four of them _ including the Bunbury Cup and Stewards` Cup _ since joining Nicholls.He landed a huge gamble at Newmarket in the autumn of 1999 but arguably ran his best race when beaten only half a length by Sampower Star in the Group Two Diadem Stakes at Ascot in September last year.Tayseer was sent out to Dubai last month and pleased his trainer on his prep run for Saturday`s US2million Dubai Golden Shaheen over six furlongs at Nad Al Sheba when fifth to Active Bo Bo in the Mahae Al Simaal over the same course and distance earlier this month.Nicholls intended to aim him at all the top sprints this year, and a spokesperson for the Thirsk trainer said: 'Tayseer was completing his final preparation before the Golden Shaheen when he sustained an irreparable fracture of his right near short pastern-boneand sadly had to be put down.'David and everyone at the stable is shocked and very upset.'