Cricket Australia is to trial injury substitutes in the first five rounds of their domestic Sheffield Shield competition. Only one substitution is available per match and must be like-for-like, such as a bowler for a bowler. If it is not like-for-like then the match referee could place restrictions on what the substitute will be able to do. "Cricket Australia management will be collecting information on the success or otherwise of the trial to assess the options post that round," said Cricket Australia head of operations Peter Roach. The opening round of the Sheffield Shield begins on Saturday.