Redknapp wrote for the London Evening Standard: "I'm told there's a strong chance Lukaku will go back to Chelsea. The transfer fee will be huge and you might look at it and think he isn't worth it but Paul Pogba's £89 million move to Manchester United from Juventus last summer changed the market completely.
"Lukaku's goal return has been good but he blows hot and cold. On a good day, he is very difficult to play against but he has too many quiet performances for me to put him up there with the best centre-forwards in the world.
"He has that same physical presence as Costa and would be the most obvious fit if Conte is going to stick with playing one up front next season. But if Lukaku does sign, it will be another case of a player leaving for next to nothing only to be re-signed a few years later for a silly amount."