The 22-year-old, an ¬£18.5million signing from AZ Alkmaar in July, was expected to play second fiddle to Kane this season but he has other ideas.
"I am ready to play. I feel bad for Harry but if he is fit I want to play with him," Janssen said.
"He is a very good player. We played some games together and it went very well. He has a lot of qualities - he is one of the best strikers in the world so it is nice to play together with him.
"I can learn a lot from him but at the end I want to play a lot with him. It is nice that he is here."