  The flux lattice melting temperature in optimally doped YBCO has been shown
to be very close to that of the onset of fluctuations around H_{c2}(T). Here,
we present a theoretical argument in support of the idea that this occurs
because the increased strength of the fluctuations as a function of magnetic
field pushes away the first order flux lattice melting transition. The argument
is based on hydrodynamic considerations (the Hansen-Verlet freezing criterion).
It is not specific to high-temperature superconductors and can be generalized
to other systems.
