Chiefs advanced to the semi-finals of the MTN8 on Saturday courtesy of goals from Dumisani Zuma, Castro and Billiat, with Ntshangase putting in a man-of-the-match performance before going off with a knock late on.
Ntshangase typically operates in an advanced role, but Solinas wants the former Black Leopards playmaker to combine more effectively with Amakhosi midfield enforcer Willard Katsande.
"Ntshangase is number 10 and he is our offensive midfielder, but I want to convert this player into a defensive midfielder as well," Solinas said on the weekend.
"He plays close with Willard Katsande, so I say to him he must also play defensive playing with two holding midfielders.
"Today in my opinion his performance was very good but he will need to improve because sometimes he likes to move forward and lose possession, and we left with Katsande in the midfield.
"Sometimes when he does that and leaves Katsande in the midfield, we don't have the situation under control. But step by step he will improve because in my opinion he has the quality."
Solinas added of Colombian striker Castro and new signing Billiat: "For me Castro is an amazing player, top player. And I don't want to take the respect of other players from other club, in my opinion he is the best player in the league.
"Billiat in my opinion can play in Europe without a problem. He can perform in Europe very well. It's a privilege for me to coach these players as they make the difference."