FBX Import Mesh Mismatch

Hi

I'm having some issues with the importing of a FBX model with multiple meshes. In my case, the ground mesh (with the grass texture) is positioned below its correct position as you can see by the following screenshots:

3DS Max 2012:

Unity:

I have created a simple Unity Package with the stated problem: DOWNLOAD

Do you know what could be causing this?

Thanks in advance