The 24-year-old, who moved from Atlanta United last month in a deal worth 21m, could make his debut tonight against Wolves.
"When you talk with him, he is ready, mentally he is ready and he says he wants to play and is available. You can see him in training, he is very dynamic, he is always involved, so that is fine," Benitez said.
"But it is the Premier League and the physicality and all those things, you have to cope with that. We will see how he feels and the other players are doing.
"We are bringing in a player who was in the MLS, so we know he needs to adapt. But he has the pace, the runs and the ability.
"We will see if he is strong enough to do the same thing as he was doing in the MLS on the ball and without the ball."
"He is different to the players we have and that is what we were looking for, running in between the lines and behind the defenders and scoring goals and making passes."