  Using high resolution X-Ray diffraction (XRD) on high purity powders, we
resolved the structure and $ab$ symmetry of the intriguing compound \svo$ $
from room temperature down to 20 K to an unprecedented level of accuracy. Upon
cooling, this new set of data unambiguously reveals a second order phase
transition lowering the symmetry from tetragonal to orthorhombic at a
temperature $T_{c2}=136$ K. The observation of an orthorhombic distortion of
the $ab$-plane is attributed to nematic phase formation supported by local
Jahn-Teller (JT) dynamical instability. At $T_{N}=105$ K, spins order and at
$T_{c1}=100$ K the tetragonal structure is recovered with an elongated c-axis.
