Fullback Mike Brown is the only back who retains his Eden Park role.
Lancaster believes the introduction of Savea and switch to fullback for Ben Smith will enhance the All Blacks attacking threats.
"Savea will definitely pose a threat through midfield as I'm sure Manu will do as well really.
"I'm sure there will be times when they get one to one and that will be a fascinating confrontation."
England saw minimal risk using Tuilagi in a position he had not held since age-group rugby. He would come under some high ball heat but the backfield was usually covered by the fullback, No8 and five-eighths.
The balance of the side had been boosted with Billy Twelvetrees and Luther Burrell in midfield, working off Danny Care and Owen Farrell.
"This is something we have wanted to do for a while," Lancaster said. "The expectations are on our backline as a whole now."
England had a backline blend of footballers who could make good decisions, strike runners with power and pace in a luxury they had not been able to compile for some time.
"It is one of the options I wanted to have a look at going into a World Cup," Lancaster added. "When you go through a World Cup, you have seven games in seven weeks you need that flexibility within your team."