  We present a study of the superconducting pairing susceptibility $K_T(r)$ for
a two-dimensional isotropic system with a strong power-law divergence in the
density of states $N(\epsilon) \sim \epsilon^{-1+\frac{1}{b}}$, $b>1$. We show
that the pair propagator has the scaling form, $K_T(r)=r^{b-3} F(T^{1/b} r)$.
An anomalous short-range behavior is found, leading straightforwardly to
positive curvature in the upper critical field, for $b\lesssim 2$ and to a zero
temperature divergence, $H_{c2} \sim T^{-2+\frac{4}{b}}$, for $b>2$.
