Andre Villas-Boas' side have a four-point cushion over their Moldovan opponents at the top of Group K and are expected to canter to victory in the capital of the breakaway state of Transnistria, where Sheriff have won the Moldovan title 11 times in the last 13 years.
But Rusnac said: "We are looking forward towards this match. Everyone is looking forward to the game, including our players, coaching staff and management.
"Tomorrow we play against one of the best teams in Europe, who occupy a leading position in one of the best championships in Europe.
"We understand that they are a team of a high European level and we understand that they are favourites not only in our group but in the whole tournament.
"Nevertheless, we are going to fight tomorrow. We prepared very seriously for this game.
"For every player of our team, it is a big opportunity to show just what we can do.
"Tomorrow, we are positive that all of our players will do their best to achieve a good result for us. We respect our opponents, but we have no fear and will fight tomorrow."