With a hefty £28 million price tag hanging over him, the pressure is on Lukaku to succeed.
However, Martinez believes it will help the ex-Chelsea man.
He said: "There is a different pressure, yes, but I think it is the opposite.
"When you sign a player from nowhere and the price is huge then straightaway there is real pressure and you feel you have to be something that you are not because of the price.
"It becomes really hard then, because the fans expect a lot more.
"With Rom, it's the opposite. We all know him, the fans know him, and he's a perfect match.
"Being able to make that effort is for Rom to feel so delighted to be able to make that effort because of the warmth he has here.
"But nothing changes, the fans know what to expect and he is full of confidence because he is so appreciate and he feels so at home.
"He is only 21, so I don't see the price tag as a negative, if anything it is going to be a positive, because he'll never have a doubt how much we love him and how much we wanted him."
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