Animate Single Axis of Rotation Only?

Hi -

I'd like to have my NavMeshAgent controlled object animate rotating on the z axis. It appears that adding an Animation with Rotation only works as all-or-nothing - either it controls the x, y, and z rotation or not at all. Is that correct, or am I missing something?

It looks like the alternative would be writing code to manually set the z axis rotation.

Am I correct that Rotation is xyz or not at all?

Thanks!