We demonstrate that the latest constraints on inflationary observables,
namely the tensor-to-scalar ratio $r$ and the scalar spectral index $n_{_S}$,
from the Cosmic Background Radiation (CMB) observations are already strong
enough to rule out the model of a scalar field with a power law potential even
in the presence of kinetic coupling to gravity with a positive coupling
constant. The case for a negative coupling constant needs special treatment.
