The Spaniard's Napoli side currently sit second behind Rudi Garcia's men - who have won all 10 of their league games this term - and Benitez feels the duo will be pushed all the way in the race for the Scudetto by Juventus, his former club Inter and Fiorentina.
"There are five teams which may be battling until the end," the ex-Liverpool boss said.
"Roma of course have an advantage, and Juventus have the strongest squad because they won the last two titles. Then there is Inter Milan, who play one match per week and also Fiorentina, who are making good performances.
"Those five teams will be battling for the Scudetto. Right now the favourite team is Roma, but I don't believe Inter Milan and Fiorentina have no chance."
Benitez went on to express his confidence that Napoli have the strength in depth to mount a serious title challenge.
"We rotate players in every match and the team is still managing to win.
"This certainly reinforces the self-confidence of the players and this is very important and is going to be even more important as the season progresses."
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