Jelavic is yet to find the net for City, but Long has settled in well and hopes he and his strike partner can score the goals to keep the Tigers in the Premier League.
"I can sense an understanding there and it's exciting," Long told the club's official website.
"Nikica is a very good player and easy to play with. The first thing we think about when we get the ball is where on the pitch the other one is.
"Although it is still early days, I think it can grow into something good."