  We present a novel experimental evidence for the odd-parity nematic
superconductivity in high-quality single crystals of doped topological
insulator Sr$_x$Bi$_2$Se$_3$. The X-ray diffraction shows that the grown single
crystals are either weakly stretched or compressed uniaxially in the basal
plane along one of the crystal axis. We show that in the superconducting state,
the upper critical magnetic field $H_{c2}$ has a two-fold rotational symmetry
and depends on the sign of the strain: in the stretched samples, the maximum of
$H_{c2}$ is achieved when the in-plane magnetic field is transverse to the
strain axis, while in the compressed samples this maximum is observed when the
field is along the strain direction. This result is naturally explained within
a framework of the odd-parity nematic superconductivity coupled to the strain.
Magnetoresistance in the normal state is independent of the current direction
and also has a two-fold rotational symmetry that demonstrates the nematicity of
the electronic system in the normal state.
