  We obtain a regularity criteria of the solution to the three-dimensional
magnetohydrodynamics system to remain smooth for all time involving only one
velocity and one vorticity component. Moreover, the norm in space and time with
which we impose our criteria for the vorticity component is at the scaling
invariant level. The proof requires a new decomposition of the four non-linear
terms making use of a new identity due to the divergence-free conditions of the
velocity and the magnetic vector fields.
