The East Coast team are the reigning champions after defeating Selangor 2-0 in last season's Malaysia League curtain raiser at the Shah Alam Stadium.
Team coach Peter Butler said although many football fans chose Kelantan as favourites to win the match, he admitted that Negeri Sembilan would not be easy to beat.
"For tomorrow's [Sunday's] match, I see our chances at 50-50. Although many predict we can win the match, I don't want that to be an excuse for my players to be complacent as Negeri Sembilan are a good team," he said after a team managers' meeting on the Charity Cup match.
Bulter who had coached Persiba Balikpapan Club in Indonesia, said Sunday's match would also serve as a test for Kelantan before they meet the Lions XII (Singapore's under-23 squad) in their first Super League match Tuesday on artificial turf at the Jalan Besar Stadium in the island republic.