Gerrard admits it is vital Rooney retains form and fitness for the World Cup this summer.
He said: “For England, I hope Wayne can sustain the way he is playing until mid-July.
“His form this season has been special and I agree with Sir Alex Ferguson in that he is now in that bracket of world class and is up there with the top players in the world.
“From England’s point of view, if Wayne can continue that kind of form until the summer, he is going to be a key player for us.
“There are a lot of good players in the England squad but, the form Wayne is in, it is vital that we can keep him fit.
“Everyone will have their fingers crossed he can avoid injury and he is fit and in this form going into the World Cup.
“At the moment, on current form, Wayne is the best player in the world, in my opinion.”