O'Connor, whose side take on Chelsea at St Andrews tomorrow, said: "Branislav is a fantastic player.
"I think he will be suited to this league. He is an athlete, is strong and powerful and he can play with the ball.
"He has got everything in his game. He is a really good player and its been a really good capture by Chelsea to get him.
"I think he will take his chance with both hands and it is a fantastic opportunity for him to come to Chelsea and play in the best league in the world. I am sure he will take it in his stride.
"He is a confident lad and I am just glad he is here in England. He can be a big star over here.
"I think his best position is right-back. He was a fantastic player for Lokomotiv. I am not sure why it never happened earlier, his move, but he will come to England and be a positive signing for Chelsea."