The forward arrived on a season-long loan from Swansea City - with a view to a permanent move - a fortnight ago, and has linked up with the squad at their training camp in Trentino.
Michu enjoyed a prolific debut season in the Premier League with Swansea, scoring 18 goals during 2012-13, but an injury-plagued campaign last time out meant the 28-year-old scored just twice in 17 appearances.
Benitez, who led the club to a third-place finish last season, believes the attacker will need time to adjust to his new role.
"He played in midfield for Rayo [Vallecano] and has scored many goals in many positions," he said.
"At Swansea he played as a second striker and as the front man.
"He needs to get know his team-mates and our type of game, but I have no doubts about him because he is smart."
Another new arrival at the club, Kalidou Koulibaly, has impressed Benitez, who believes the team will be stronger during the upcoming campaign.
"He is very attentive, listens and has surprised me positively. He has learnt Italian and his acclimatisation will be faster.
"The squad is strong and can be stronger if [Juan Camilo] Zuniga, [Giandomenico] Mesto, [Christian] Maggio and [Marek] Hamsik are at their level that was missing last year."
