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Massimiliano Allegri says he will need "a year or two" to make Juventus Serie A title contenders ahead of Sunday's crunch clash at Roma.
Juve boss Allegri won five consecutive league titles during his previous spell at the club, but took on a rebuilding job when he returned to Turin last May.
The Bianconeri are fifth in the table ahead of their trip to the Eternal City, 11 points adrift of leaders Inter and the champions have a game in hand.
Allegri reiterated that he will need time to make Juve a huge force once again.
"I came here knowing that this year we needed to start changing the team, [in order to] be back challenging for the title in a year or two," Allegri said.
"We could have done better so far, but it's a matter of experience, it's normal to pay for our mistakes.
"In football, things don't miraculously change in a short time."
Juve are three points ahead of Roma and Allegri is expecting a huge battle with Jose Mourinho's side.
"Tomorrow will be an important match," he continued. "Roma have excellent individuals and a coach capable of preparing them in the best possible way. Competitiveness and technique will be key.
"Against Napoli we expected to win and get within two points of them, coming from a positive period, but we still kept the gap unchanged. We need to improve the quality of our passes, but we are growing. January will be important.
"We are working to improve our game. We want to reach our Champions League goal, and then there are still many other ambitions.
"To win, you need to have quality as well as technique, and it is only with experience that you learn that."
Allegri will be absent from the touchline for the encounter with Roma, after being handed a one-match ban and a €10,000 fine by the Italian Football Federation following a furious outburst at referee Simone Sozza at the end of the 1-1 draw with Napoli on Thursday.
Juve have the opportunity to win three consecutive league games against the Giallorossi for the first time since 2014.