Udinese won 4-0 via goals from Brenner, Florian Thauvin, Lorenzo Lucca and Keinan Davis.
Rujaic later said: "First of all, I'm happy with our first victory in our stadium. It was a solid match, where I saw good plots and many things tried in training, but I'm happy because we played in front of our crowd and won.
"I'm happy that all the attackers scored, but every goal came from collective actions. We were playing against a serious and experienced team like Avellino, who I went to watch against Juve Stabia Avellino defended well, pressing a lot, but it was clear that as time passed they couldn't continue like this and little by little the team found its rhythm."
He continued: "Clearly we want possession of the ball, managing it well, today we did it discreetly, Okoye limited the long balls even if balance will be needed, we won't always be able to play short. But for being the first step we are happy.
"There has been progress in this, clearly there is always room for improvement but the wingers in my job do a lot of work, today Avellino didn't find their usual exchanges even on the flanks."