The teenager is due to join the Catalan outfit from Dinamo Zagreb at the end of the season and Suker has compared the youngster to Lionel Messi.
"Halilovic is a star," he told Cope.
"He reminds me of Messi. He is young, but we can trust him and he handles the ball very well."
It is believed that Barcelona are still confident that the deal will go through despite their current transfer ban.