Paulo Dybala scored twice, with Artem Dovbyk also on the scoresheet.
“I don't know if it's Roma's best of the season, but I know we have to improve,” Ranieri told DAZN.
“The boys had to blow off the second half against Como, they did that and now we can have a nice Christmas, but after that we have to do better because Roma haven't won away from home in Serie A for eight months.
“It's not right that we have one Roma at home and one away, we have to wake up and do better.
“I have always said that Paulo (Dybala) plays when he is in shape. If he seems tired or that the game needs something else, I take him off. Jose Mourinho said it and so did I, there is one Roma with Dybala and one without.”
He also said about Mats Hummels and Leandro Paredes: “What can I say? Hummels is a World Cup winner, he played a Champions League final. He had the flu all week and barely trained, but if he says he can play, I'll play him.
“Paredes is the same, an incredible playmaker who only needs one or two touches. These are the players I like, they have experience and can set the pace.”
Comments