  After being expected as a promising analogue to cuprates for decades,
superconductivity was recently discovered in infinite-layer nickelates,
providing new opportunities to explore mechanisms of high-temperature
superconductivity. However, in sharp contrast to the single-band
quasi-two-dimensional superconductivity in cuprates, nickelates exhibit a
multi-band electronic structure and an unexpected isotropic superconductivity
as reported recently, which challenges the cuprate-like picture in nickelates.
Here, we show the superconductivity in nickelates is actually anisotropic and
quasi-two-dimensional in nature, as that in cuprates. By synthesizing
high-quality lanthanide nickelate films with enhanced crystallinity and
superconductivity ($T_{c}^{onset}$ = 18.8 K, $T_{c}^{zero}$ = 16.5 K), strong
anisotropic magnetotransport behaviors have been observed. The
quasi-two-dimensional nature is further confirmed by the existence of a
cusp-like peak of the angle-dependent $T_{c}$, and a
Berezinskii-Kosterlitz-Thouless transition near $T_{c}$. Our work thus suggests
a quasi-two-dimensional superconductivity in infinite-layer nickelates,
implying a single-3$d_{x^2-y^2}$-band cuprate-like picture may remain valid in
these compounds.
