  We report on ESO--VLT adaptive optics imaging of one radio-loud quasar at z
$\sim$ 3. In spite of the large distance of the object we are able to detect
its surrounding extended nebulosity the properties of which are consistent with
an underlying massive galaxy of M$_K$ $\sim$ --27 and effective radius R$_e$ =
7 kpc. As far as we know this is the clearest detection of a radio loud quasar
host at high redshift. The host luminosity is indicative of the existence of
massive spheroids even at this early cosmic epoch. The host luminosity is about
1 magnitude fainter than the expected value based on the average trend of the
host galaxies of RLQ at lower redshift. The result, which however is based on a
single object, suggests that at z $\sim$ 3 there is a deviation from a
luminosity--redshift dependence regulated only by passive evolution.
