Benitez said: "Xabi is in the squad. He will not be in the starting eleven but he will be in the squad because he is an important player and he is now training with the team.
"He is not 100 per cent fit and the idea is not to use him against Juventus because we hope to be playing well and winning. But if we are not and we need something different at the end of the game, then we may think about using him."
Alonso has not played since having his ankle broke by fat Frank Lampard on New Year's Day.