  The object transiting the star Kepler-91 was recently assessed as being of
planetary nature. The confirmation was achieved by analysing the light-curve
modulations observed in the Kepler data. However, quasi-simultaneous studies
claimed a self-luminous nature for this object, thus rejecting it as a planet.
In this work, we apply an {independent} approach to confirm the planetary mass
of Kepler-91b by using multi-epoch high-resolution spectroscopy obtained with
the Calar Alto Fiber-fed Echelle spectrograph (CAFE). We obtain the physical
and orbital parameters with the radial velocity technique. In particular, we
derive a value of $1.09 \pm 0.20\,M_{\mathrm{Jup}}$ for the mass of Kepler-91b,
in excellent agreement with our previous estimate that was based on the orbital
brightness modulation.
