The A-League's Usain Bolt experiment shouldn't come at a cost to young Australian talent, according to Adelaide United coach Marco Kurz.
Kurz says he can't pass judgement on Bolt as a footballer but believes the A-League should increase the match day squads to 18 so younger local players get a look in.
"It's up to ... Usain Bolt but if you will improve the league then you must bring quality," Kurz told reporters on Monday.
"And he must have a higher quality than the players that are here - that is, for me, the point.
"If it's only to bring some more supporters on the game day in the stadium, it's for me not the right way.
"Why not (expand) the squad for the game day to 18 players and then you can put two young players in the squad and they can have play time.
"Because I think the aim for the league must be to improve young Australian players and not to to bring a sprinter in (their) position."
Bolt is currently on an indefinite trial with Central Coast Mariners.
Kurz said he was as interested as anyone to see if the eight-time Olympic gold medallist could cut it as a professional footballer.
"I will see what is the next step of Usain Bolt but for sure he must have the quality to play ... he is fast enough but I don't know about Usain if he is good on the ball or not," the German said.
"I know him as a perfect sprinter but not as a footballer."
Australian Associated Press